def closest_integer(value):
    '''
    Create a function that takes a value (string) representing a number
    and returns the closest integer to it. If the number is equidistant
    from two integers, round it away from zero.

    Examples
    >>> closest_integer("10")
    10
    >>> closest_integer("15.3")
    15

    Note:
    Rounding away from zero means that if the given number is equidistant
    from two integers, the one you should return is the one that is the
    farthest from zero. For example closest_integer("14.5") should
    return 15 and closest_integer("-14.5") should return -15.
    '''

def closest_integer(value):
    '''
    Parse a numeric string and round it to the nearest integer, following the rule of rounding half away from zero (i.e., .5 rounds to the integer with larger absolute value).

    Examples
    >>> closest_integer("10")
    10
    >>> closest_integer("15.3")
    15

    Note:
    Rounding away from zero means that if the given number is equidistant
    from two integers, the one you should return is the one that is the
    farthest from zero. For example closest_integer("14.5") should
    return 15 and closest_integer("-14.5") should return -15.
    '''

Answer:
    from math import floor, ceil

    if value.count('.') == 1:
        # remove trailing zeros
        while (value[-1] == '0'):
            value = value[:-1]

    num = float(value)
    if value[-2:] == '.5':
        if num > 0:
            res = ceil(num)
        else:
            res = floor(num)
    elif len(value) > 0:
        res = int(round(num))
    else:
        res = 0

    return res

def check(candidate):

    # Check some simple cases
    assert candidate("10") == 10, "Test 1"
    assert candidate("14.5") == 15, "Test 2"
    assert candidate("-15.5") == -16, "Test 3"
    assert candidate("15.3") == 15, "Test 3"

    # Check some edge cases that are easy to work out by hand.
    assert candidate("0") == 0, "Test 0"


def make_a_pile(n):
    """
    Given a positive integer n, you have to make a pile of n levels of stones.
    The first level has n stones.
    The number of stones in the next level is:
        - the next odd number if n is odd.
        - the next even number if n is even.
    Return the number of stones in each level in a list, where element at index
    i represents the number of stones in the level (i+1).

    Examples:
    >>> make_a_pile(3)
    [3, 5, 7]
    """

def make_a_pile(n):
    """
    Construct a tiered stack of stones with n levels. The uppermost level has n stones.
    For each subsequent level, if the preceding level has an odd number of stones,
    the next level gets the following odd number; if even, the next even number.
    Return a list where the index corresponds to the level number (starting from 0 for the top).
    >>> make_a_pile(3)
    [3, 5, 7]
    """

Answer: return [n + 2*i for i in range(n)]

def check(candidate):

    # Check some simple cases
    assert candidate(3) == [3, 5, 7], "Test 3"
    assert candidate(4) == [4,6,8,10], "Test 4"
    assert candidate(5) == [5, 7, 9, 11, 13]
    assert candidate(6) == [6, 8, 10, 12, 14, 16]
    assert candidate(8) == [8, 10, 12, 14, 16, 18, 20, 22]

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def words_string(s):
    """
    You will be given a string of words separated by commas or spaces. Your task is
    to split the string into words and return an array of the words.

    For example:
    words_string("Hi, my name is John") == ["Hi", "my", "name", "is", "John"]
    words_string("One, two, three, four, five, six") == ["One", "two", "three", "four", "five", "six"]
    """

def words_string(s):
    """
    Parse a string that contains words separated by either commas or spaces.
    Extract and return an array containing each individual word in the original order.
    For example:
    words_string("Hi, my name is John") == ["Hi", "my", "name", "is", "John"]
    words_string("One, two, three, four, five, six") == ["One", "two", "three", "four", "five", "six"]
    """

Answer:
    if not s:
        return []

    s_list = []

    for letter in s:
        if letter == ',':
            s_list.append(' ')
        else:
            s_list.append(letter)

    s_list = "".join(s_list)
    return s_list.split()

def check(candidate):

    # Check some simple cases
    assert True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate("Hi, my name is John") == ["Hi", "my", "name", "is", "John"]
    assert candidate("One, two, three, four, five, six") == ["One", "two", "three", "four", "five", "six"]
    assert candidate("Hi, my name") == ["Hi", "my", "name"]
    assert candidate("One,, two, three, four, five, six,") == ["One", "two", "three", "four", "five", "six"]

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate("") == []
    assert candidate("ahmed     , gamal") == ["ahmed", "gamal"]


def choose_num(x, y):
    """This function takes two positive numbers x and y and returns the
    biggest even integer number that is in the range [x, y] inclusive. If
    there's no such number, then the function should return -1.

    For example:
    choose_num(12, 15) = 14
    choose_num(13, 12) = -1
    """

def choose_num(x, y):
    """Given two positive integers x and y, determine the largest even integer
    that lies within the inclusive interval [x, y]. If no such number exists,
    return -1.
    For example:
    choose_num(12, 15) = 14
    choose_num(13, 12) = -1
    """

Answer:
    if x > y:
        return -1
    if y % 2 == 0:
        return y
    if x == y:
        return -1
    return y - 1

def check(candidate):

    # Check some simple cases
    assert candidate(12, 15) == 14
    assert candidate(13, 12) == -1
    assert candidate(33, 12354) == 12354
    assert candidate(5234, 5233) == -1
    assert candidate(6, 29) == 28
    assert candidate(27, 10) == -1

    # Check some edge cases that are easy to work out by hand.
    assert candidate(7, 7) == -1
    assert candidate(546, 546) == 546


def rounded_avg(n, m):
    """You are given two positive integers n and m, and your task is to compute the
    average of the integers from n through m (including n and m).
    Round the answer to the nearest integer and convert that to binary.
    If n is greater than m, return -1.
    Example:
    rounded_avg(1, 5) => "0b11"
    rounded_avg(7, 5) => -1
    rounded_avg(10, 20) => "0b1111"
    rounded_avg(20, 33) => "0b11010"
    """

def rounded_avg(n, m):
    """Compute the arithmetic mean of all integers from n to m inclusive,
    round the result to the nearest integer, then convert that integer to
    its binary representation prefixed with '0b'. If n > m, return -1.
    Example:
    rounded_avg(1, 5) => "0b11"
    rounded_avg(7, 5) => -1
    rounded_avg(10, 20) => "0b1111"
    rounded_avg(20, 33) => "0b11010"
    """

Answer:
    if m < n:
        return -1
    summation = 0
    for i in range(n, m+1):
        summation += i
    return bin(round(summation/(m - n + 1)))

def check(candidate):

    # Check some simple cases
    assert candidate(1, 5) == "0b11"
    assert candidate(7, 13) == "0b1010"
    assert candidate(964,977) == "0b1111001010"
    assert candidate(996,997) == "0b1111100100"
    assert candidate(560,851) == "0b1011000010"
    assert candidate(185,546) == "0b101101110"
    assert candidate(362,496) == "0b110101101"
    assert candidate(350,902) == "0b1001110010"
    assert candidate(197,233) == "0b11010111"

    # Check some edge cases that are easy to work out by hand.
    assert candidate(7, 5) == -1
    assert candidate(5, 1) == -1
    assert candidate(5, 5) == "0b101"


def unique_digits(x):
    """Given a list of positive integers x. return a sorted list of all
    elements that hasn't any even digit.

    Note: Returned list should be sorted in increasing order.

    For example:
    >>> unique_digits([15, 33, 1422, 1])
    [1, 15, 33]
    >>> unique_digits([152, 323, 1422, 10])
    []
    """

def unique_digits(x):
    """Given a list of positive integers, filter out all numbers that contain
    at least one even digit. Return the remaining numbers sorted in ascending order.
    For example:
    >>> unique_digits([15, 33, 1422, 1])
    [1, 15, 33]
    >>> unique_digits([152, 323, 1422, 10])
    []
    """

Answer:
    odd_digit_elements = []
    for i in x:
        if all (int(c) % 2 == 1 for c in str(i)):
            odd_digit_elements.append(i)
    return sorted(odd_digit_elements)

def check(candidate):

    # Check some simple cases
    assert candidate([15, 33, 1422, 1]) == [1, 15, 33]
    assert candidate([152, 323, 1422, 10]) == []
    assert candidate([12345, 2033, 111, 151]) == [111, 151]
    assert candidate([135, 103, 31]) == [31, 135]

    # Check some edge cases that are easy to work out by hand.
    assert True


def by_length(arr):
    """
    Given an array of integers, sort the integers that are between 1 and 9 inclusive,
    reverse the resulting array, and then replace each digit by its corresponding name from
    "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine".

    For example:
      arr = [2, 1, 1, 4, 5, 8, 2, 3]
            -> sort arr -> [1, 1, 2, 2, 3, 4, 5, 8]
            -> reverse arr -> [8, 5, 4, 3, 2, 2, 1, 1]
      return ["Eight", "Five", "Four", "Three", "Two", "Two", "One", "One"]

      If the array is empty, return an empty array:
      arr = []
      return []

      If the array has any strange number ignore it:
      arr = [1, -1 , 55]
            -> sort arr -> [-1, 1, 55]
            -> reverse arr -> [55, 1, -1]
      return = ['One']
    """

def by_length(arr):
    """
    From the input array, extract all integers that fall between 1 and 9 inclusive.
    Sort them ascending, then reverse the order. Finally, replace each numeric digit
    with its English word representation (e.g., 1 -> "One", 2 -> "Two", ... 9 -> "Nine").
    If the original array is empty, return an empty list. Ignore numbers outside the 1-9 range.
    For example:
      arr = [2, 1, 1, 4, 5, 8, 2, 3]
            -> sort arr -> [1, 1, 2, 2, 3, 4, 5, 8]
            -> reverse arr -> [8, 5, 4, 3, 2, 2, 1, 1]
      return ["Eight", "Five", "Four", "Three", "Two", "Two", "One", "One"]

      If the array is empty, return an empty array:
      arr = []
      return []

      If the array has any strange number ignore it:
      arr = [1, -1 , 55]
            -> sort arr -> [-1, 1, 55]
            -> reverse arr -> [55, 1, -1]
      return = ['One']
    """

Answer:
    dic = {
        1: "One",
        2: "Two",
        3: "Three",
        4: "Four",
        5: "Five",
        6: "Six",
        7: "Seven",
        8: "Eight",
        9: "Nine",
    }
    sorted_arr = sorted(arr, reverse=True)
    new_arr = []
    for var in sorted_arr:
        try:
            new_arr.append(dic[var])
        except:
            pass
    return new_arr

def check(candidate):

    # Check some simple cases
    assert True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([2, 1, 1, 4, 5, 8, 2, 3]) == ["Eight", "Five", "Four", "Three", "Two", "Two", "One", "One"], "Error"
    assert candidate([]) == [], "Error"
    assert candidate([1, -1 , 55]) == ['One'], "Error"

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([1, -1, 3, 2]) == ["Three", "Two", "One"]
    assert candidate([9, 4, 8]) == ["Nine", "Eight", "Four"]


def f(n):
    """ Implement the function f that takes n as a parameter,
    and returns a list of size n, such that the value of the element at index i is the factorial of i if i is even
    or the sum of numbers from 1 to i otherwise.
    i starts from 1.
    the factorial of i is the multiplication of the numbers from 1 to i (1 * 2 * ... * i).
    Example:
    f(5) == [1, 2, 6, 24, 15]
    """

def f(n):
    """ Build a list of length n where the element at each index i (starting from 1)
    is the factorial of i if i is even, or the sum of integers from 1 to i if i is odd.
    Example:
    f(5) == [1, 2, 6, 24, 15]
    """

Answer:
    ret = []
    for i in range(1,n+1):
        if i%2 == 0:
            x = 1
            for j in range(1,i+1): x *= j
            ret += [x]
        else:
            x = 0
            for j in range(1,i+1): x += j
            ret += [x]
    return ret

def check(candidate):

    assert candidate(5) == [1, 2, 6, 24, 15]
    assert candidate(7) == [1, 2, 6, 24, 15, 720, 28]
    assert candidate(1) == [1]
    assert candidate(3) == [1, 2, 6]


def even_odd_palindrome(n):
    """
    Given a positive integer n, return a tuple that has the number of even and odd
    integer palindromes that fall within the range(1, n), inclusive.

    Example 1:

        Input: 3
        Output: (1, 2)
        Explanation:
        Integer palindrome are 1, 2, 3. one of them is even, and two of them are odd.

    Example 2:

        Input: 12
        Output: (4, 6)
        Explanation:
        Integer palindrome are 1, 2, 3, 4, 5, 6, 7, 8, 9, 11. four of them are even, and 6 of them are odd.

    Note:
        1. 1 <= n <= 10^3
        2. returned tuple has the number of even and odd integer palindromes respectively.
    """

def even_odd_palindrome(n):
    """
    Count how many even and odd integer palindromes exist in the range 1 to n inclusive.
    Return a tuple (even_count, odd_count).
    Example 1:
        Input: 3
        Output: (1, 2)
        Explanation: Palindromes are 1,2,3; even count 1, odd count 2.
    Example 2:
        Input: 12
        Output: (4, 6)
        Explanation: Palindromes up to 12: 1..9,11; evens: 2,4,6,8 => 4; odds: 1,3,5,7,9,11 => 6.
    Note:
        1. 1 <= n <= 10^3
        2. returned tuple has the number of even and odd integer palindromes respectively.
    """

Answer:
    def is_palindrome(n):
        return str(n) == str(n)[::-1]

    even_palindrome_count = 0
    odd_palindrome_count = 0

    for i in range(1, n+1):
        if i%2 == 1 and is_palindrome(i):
                odd_palindrome_count += 1
        elif i%2 == 0 and is_palindrome(i):
            even_palindrome_count += 1
    return (even_palindrome_count, odd_palindrome_count)

def check(candidate):

    # Check some simple cases
    assert candidate(123) == (8, 13)
    assert candidate(12) == (4, 6)
    assert candidate(3) == (1, 2)
    assert candidate(63) == (6, 8)
    assert candidate(25) == (5, 6)
    assert candidate(19) == (4, 6)
    assert candidate(9) == (4, 5), "This prints if this assert fails 1 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate(1) == (0, 1), "This prints if this assert fails 2 (also good for debugging!)"


def count_nums(arr):
    """
    Write a function count_nums which takes an array of integers and returns
    the number of elements which has a sum of digits > 0.
    If a number is negative, then its first signed digit will be negative:
    e.g. -123 has signed digits -1, 2, and 3.
    >>> count_nums([]) == 0
    >>> count_nums([-1, 11, -11]) == 1
    >>> count_nums([1, 1, 2]) == 3
    """

def count_nums(arr):
    """
    Count the number of elements in the array for which the sum of its signed digits
    is greater than 0. For negative numbers, the first digit is considered negative
    (e.g., -123 has signed digits -1, 2, 3).
    >>> count_nums([]) == 0
    >>> count_nums([-1, 11, -11]) == 1
    >>> count_nums([1, 1, 2]) == 3
    """

Answer:
    def digits_sum(n):
        neg = 1
        if n < 0: n, neg = -1 * n, -1
        n = [int(i) for i in str(n)]
        n[0] = n[0] * neg
        return sum(n)
    return len(list(filter(lambda x: x > 0, [digits_sum(i) for i in arr])))

def check(candidate):

    # Check some simple cases
    assert candidate([]) == 0
    assert candidate([-1, -2, 0]) == 0
    assert candidate([1, 1, 2, -2, 3, 4, 5]) == 6
    assert candidate([1, 6, 9, -6, 0, 1, 5]) == 5
    assert candidate([1, 100, 98, -7, 1, -1]) == 4
    assert candidate([12, 23, 34, -45, -56, 0]) == 5
    assert candidate([-0, 1**0]) == 1
    assert candidate([1]) == 1

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def move_one_ball(arr):
    """We have an array 'arr' of N integers arr[1], arr[2], ..., arr[N].The
    numbers in the array will be randomly ordered. Your task is to determine if
    it is possible to get an array sorted in non-decreasing order by performing
    the following operation on the given array:
        You are allowed to perform right shift operation any number of times.

    One right shift operation means shifting all elements of the array by one
    position in the right direction. The last element of the array will be moved to
    the starting position in the array i.e. 0th index.

    If it is possible to obtain the sorted array by performing the above operation
    then return True else return False.
    If the given array is empty then return True.

    Note: The given list is guaranteed to have unique elements.

    For Example:

    move_one_ball([3, 4, 5, 1, 2])==>True
    Explanation: By performin 2 right shift operations, non-decreasing order can
                 be achieved for the given array.
    move_one_ball([3, 5, 4, 1, 2])==>False
    Explanation:It is not possible to get non-decreasing order for the given
                array by performing any number of right shift operations.

    """

def move_one_ball(arr):
    """Determine if the array can be sorted in non-decreasing order by performing
    any number of right cyclic shifts (i.e., moving the last element to the front).
    Return True if possible, otherwise False. An empty array is considered True.
    The array contains unique elements.
    For Example:
    move_one_ball([3, 4, 5, 1, 2])==>True
    Explanation: After 2 right shifts, we get [1,2,3,4,5].
    move_one_ball([3, 5, 4, 1, 2])==>False
    Explanation: No number of right shifts yields a sorted order.
    """

Answer:
    if len(arr)==0:
      return True
    sorted_array=sorted(arr)
    my_arr=[]

    min_value=min(arr)
    min_index=arr.index(min_value)
    my_arr=arr[min_index:]+arr[0:min_index]
    for i in range(len(arr)):
      if my_arr[i]!=sorted_array[i]:
        return False
    return True

def check(candidate):

    # Check some simple cases
    assert candidate([3, 4, 5, 1, 2])==True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([3, 5, 10, 1, 2])==True
    assert candidate([4, 3, 1, 2])==False
    # Check some edge cases that are easy to work out by hand.
    assert candidate([3, 5, 4, 1, 2])==False, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([])==True


def exchange(lst1, lst2):
    """In this problem, you will implement a function that takes two lists of numbers,
    and determines whether it is possible to perform an exchange of elements
    between them to make lst1 a list of only even numbers.
    There is no limit on the number of exchanged elements between lst1 and lst2.
    If it is possible to exchange elements between the lst1 and lst2 to make
    all the elements of lst1 to be even, return "YES".
    Otherwise, return "NO".
    For example:
    exchange([1, 2, 3, 4], [1, 2, 3, 4]) => "YES"
    exchange([1, 2, 3, 4], [1, 5, 3, 4]) => "NO"
    It is assumed that the input lists will be non-empty.
    """

def exchange(lst1, lst2):
    """Determine whether it's possible, by swapping any number of elements between
    the two lists, to make all elements in lst1 even. Return "YES" if possible,
    otherwise "NO". The lists are non-empty.
    For example:
    exchange([1, 2, 3, 4], [1, 2, 3, 4]) => "YES"
    exchange([1, 2, 3, 4], [1, 5, 3, 4]) => "NO"
    """

Answer:
    odd = 0
    even = 0
    for i in lst1:
        if i%2 == 1:
            odd += 1
    for i in lst2:
        if i%2 == 0:
            even += 1
    if even >= odd:
        return "YES"
    return "NO"

def check(candidate):

    # Check some simple cases
    assert candidate([1, 2, 3, 4], [1, 2, 3, 4]) == "YES"
    assert candidate([1, 2, 3, 4], [1, 5, 3, 4]) == "NO"
    assert candidate([1, 2, 3, 4], [2, 1, 4, 3]) == "YES"
    assert candidate([5, 7, 3], [2, 6, 4]) == "YES"
    assert candidate([5, 7, 3], [2, 6, 3]) == "NO"
    assert candidate([3, 2, 6, 1, 8, 9], [3, 5, 5, 1, 1, 1]) == "NO"

    # Check some edge cases that are easy to work out by hand.
    assert candidate([100, 200], [200, 200]) == "YES"


def histogram(test):
    """Given a string representing a space separated lowercase letters, return a dictionary
    of the letter with the most repetition and containing the corresponding count.
    If several letters have the same occurrence, return all of them.

    Example:
    histogram('a b c') == {'a': 1, 'b': 1, 'c': 1}
    histogram('a b b a') == {'a': 2, 'b': 2}
    histogram('a b c a b') == {'a': 2, 'b': 2}
    histogram('b b b b a') == {'b': 4}
    histogram('') == {}

    """

def histogram(test):
    """Given a string of space-separated lowercase letters, produce a dictionary
    mapping each letter to its frequency, but only include letters with the maximum
    frequency. If all letters are unique, include all of them with count 1.
    Example:
    histogram('a b c') == {'a': 1, 'b': 1, 'c': 1}
    histogram('a b b a') == {'a': 2, 'b': 2}
    histogram('a b c a b') == {'a': 2, 'b': 2}
    histogram('b b b b a') == {'b': 4}
    histogram('') == {}
    """

Answer:
    dict1={}
    list1=test.split(" ")
    t=0

    for i in list1:
        if(list1.count(i)>t) and i!='':
            t=list1.count(i)
    if t>0:
        for i in list1:
            if(list1.count(i)==t):

                dict1[i]=t
    return dict1

def check(candidate):

    # Check some simple cases
    assert candidate('a b b a') == {'a':2,'b': 2}, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate('a b c a b') == {'a': 2, 'b': 2}, "This prints if this assert fails 2 (good for debugging!)"
    assert candidate('a b c d g') == {'a': 1, 'b': 1, 'c': 1, 'd': 1, 'g': 1}, "This prints if this assert fails 3 (good for debugging!)"
    assert candidate('r t g') == {'r': 1,'t': 1,'g': 1}, "This prints if this assert fails 4 (good for debugging!)"
    assert candidate('b b b b a') == {'b': 4}, "This prints if this assert fails 5 (good for debugging!)"
    assert candidate('r t g') == {'r': 1,'t': 1,'g': 1}, "This prints if this assert fails 6 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate('') == {}, "This prints if this assert fails 7 (also good for debugging!)"
    assert candidate('a') == {'a': 1}, "This prints if this assert fails 8 (also good for debugging!)"


def reverse_delete(s,c):
    """Task
    We are given two strings s and c, you have to deleted all the characters in s that are equal to any character in c
    then check if the result string is palindrome.
    A string is called palindrome if it reads the same backward as forward.
    You should return a tuple containing the result string and True/False for the check.
    Example
    For s = "abcde", c = "ae", the result should be ('bcd',False)
    For s = "abcdef", c = "b"  the result should be ('acdef',False)
    For s = "abcdedcba", c = "ab", the result should be ('cdedc',True)
    """

def reverse_delete(s,c):
    """Remove from string s every character that appears in string c,
    then check if the resulting string is a palindrome. Return a tuple
    (filtered_string, is_palindrome).
    Example:
    For s = "abcde", c = "ae", the result should be ('bcd', False)
    For s = "abcdef", c = "b"  the result should be ('acdef', False)
    For s = "abcdedcba", c = "ab", the result should be ('cdedc', True)
    """

Answer:
    s = ''.join([char for char in s if char not in c])
    return (s,s[::-1] == s)

def check(candidate):

    assert candidate("abcde","ae") == ('bcd',False)
    assert candidate("abcdef", "b") == ('acdef',False)
    assert candidate("abcdedcba","ab") == ('cdedc',True)
    assert candidate("dwik","w") == ('dik',False)
    assert candidate("a","a") == ('',True)
    assert candidate("abcdedcba","") == ('abcdedcba',True)
    assert candidate("abcdedcba","v") == ('abcdedcba',True)
    assert candidate("vabba","v") == ('abba',True)
    assert candidate("mamma", "mia") == ("", True)


def odd_count(lst):
    """Given a list of strings, where each string consists of only digits, return a list.
    Each element i of the output should be "the number of odd elements in the
    string i of the input." where all the i's should be replaced by the number
    of odd digits in the i'th string of the input.

    >>> odd_count(['1234567'])
    ["the number of odd elements 4n the str4ng 4 of the 4nput."]
    >>> odd_count(['3',"11111111"])
    ["the number of odd elements 1n the str1ng 1 of the 1nput.",
     "the number of odd elements 8n the str8ng 8 of the 8nput."]
    """

def odd_count(lst):
    """For each string in the input list (each consisting solely of digits),
    count the number of odd digits. Then produce a corresponding list of strings
    where each string is of the form "the number of odd elements i in the string i of the input."
    with i replaced by the count.
    >>> odd_count(['1234567'])
    ["the number of odd elements 4n the str4ng 4 of the 4nput."]
    >>> odd_count(['3',"11111111"])
    ["the number of odd elements 1n the str1ng 1 of the 1nput.",
     "the number of odd elements 8n the str8ng 8 of the 8nput."]
    """

Answer:
    res = []
    for arr in lst:
        n = sum(int(d)%2==1 for d in arr)
        res.append("the number of odd elements " + str(n) + "n the str"+ str(n) +"ng "+ str(n) +" of the "+ str(n) +"nput.")
    return res

def check(candidate):

    # Check some simple cases
    assert candidate(['1234567']) == ["the number of odd elements 4n the str4ng 4 of the 4nput."], "Test 1"
    assert candidate(['3',"11111111"]) == ["the number of odd elements 1n the str1ng 1 of the 1nput.", "the number of odd elements 8n the str8ng 8 of the 8nput."], "Test 2"
    assert candidate(['271', '137', '314']) == [
        'the number of odd elements 2n the str2ng 2 of the 2nput.',
        'the number of odd elements 3n the str3ng 3 of the 3nput.',
        'the number of odd elements 2n the str2ng 2 of the 2nput.'
    ]

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def minSubArraySum(nums):
    """
    Given an array of integers nums, find the minimum sum of any non-empty sub-array
    of nums.
    Example
    minSubArraySum([2, 3, 4, 1, 2, 4]) == 1
    minSubArraySum([-1, -2, -3]) == -6
    """

def minSubArraySum(nums):
    """Find the minimum sum of any contiguous non-empty subarray within the given array.
    Example
    minSubArraySum([2, 3, 4, 1, 2, 4]) == 1
    minSubArraySum([-1, -2, -3]) == -6
    """

Answer:
    max_sum = 0
    s = 0
    for num in nums:
        s += -num
        if (s < 0):
            s = 0
        max_sum = max(s, max_sum)
    if max_sum == 0:
        max_sum = max(-i for i in nums)
    min_sum = -max_sum
    return min_sum

def check(candidate):

    # Check some simple cases
    assert candidate([2, 3, 4, 1, 2, 4]) == 1, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([-1, -2, -3]) == -6
    assert candidate([-1, -2, -3, 2, -10]) == -14
    assert candidate([-9999999999999999]) == -9999999999999999
    assert candidate([0, 10, 20, 1000000]) == 0
    assert candidate([-1, -2, -3, 10, -5]) == -6
    assert candidate([100, -1, -2, -3, 10, -5]) == -6
    assert candidate([10, 11, 13, 8, 3, 4]) == 3
    assert candidate([100, -33, 32, -1, 0, -2]) == -33

    # Check some edge cases that are easy to work out by hand.
    assert candidate([-10]) == -10, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([7]) == 7
    assert candidate([1, -1]) == -1


def max_fill(grid, capacity):
    import math
    """
    You are given a rectangular grid of wells. Each row represents a single well,
    and each 1 in a row represents a single unit of water.
    Each well has a corresponding bucket that can be used to extract water from it,
    and all buckets have the same capacity.
    Your task is to use the buckets to empty the wells.
    Output the number of times you need to lower the buckets.

    Example 1:
        Input:
            grid : [[0,0,1,0], [0,1,0,0], [1,1,1,1]]
            bucket_capacity : 1
        Output: 6

    Example 2:
        Input:
            grid : [[0,0,1,1], [0,0,0,0], [1,1,1,1], [0,1,1,1]]
            bucket_capacity : 2
        Output: 5

    Example 3:
        Input:
            grid : [[0,0,0], [0,0,0]]
            bucket_capacity : 5
        Output: 0

    Constraints:
        * all wells have the same length
        * 1 <= grid.length <= 10^2
        * 1 <= grid[:,1].length <= 10^2
        * grid[i][j] -> 0 | 1
        * 1 <= capacity <= 10
    """

def max_fill(grid, capacity):
    import math
    """Calculate the minimum number of bucket-lowering operations required
    to remove all water (represented by 1s) from a rectangular grid of wells.
    Each row is a well; each bucket has a fixed capacity. You can lower a bucket
    into one well at a time, and it collects up to 'capacity' units of water
    from that well. Return the total number of bucket lowers needed.
    Example 1:
        Input:
            grid : [[0,0,1,0], [0,1,0,0], [1,1,1,1]]
            bucket_capacity : 1
        Output: 6
    Example 2:
        Input:
            grid : [[0,0,1,1], [0,0,0,0], [1,1,1,1], [0,1,1,1]]
            bucket_capacity : 2
        Output: 5
    Example 3:
        Input:
            grid : [[0,0,0], [0,0,0]]
            bucket_capacity : 5
        Output: 0
    Constraints:
        * all wells have the same length
        * 1 <= grid.length <= 10^2
        * 1 <= grid[:,1].length <= 10^2
        * grid[i][j] -> 0 | 1
        * 1 <= capacity <= 10
    """

Answer: return sum([math.ceil(sum(arr)/capacity) for arr in grid])

def check(candidate):

    # Check some simple cases
    assert True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([[0,0,1,0], [0,1,0,0], [1,1,1,1]], 1) == 6, "Error"
    assert candidate([[0,0,1,1], [0,0,0,0], [1,1,1,1], [0,1,1,1]], 2) == 5, "Error"
    assert candidate([[0,0,0], [0,0,0]], 5) == 0, "Error"

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([[1,1,1,1], [1,1,1,1]], 2) == 4, "Error"
    assert candidate([[1,1,1,1], [1,1,1,1]], 9) == 2, "Error"


def sort_array(arr):
    """
    In this Kata, you have to sort an array of non-negative integers according to
    number of ones in their binary representation in ascending order.
    For similar number of ones, sort based on decimal value.

    It must be implemented like this:
    >>> sort_array([1, 5, 2, 3, 4]) == [1, 2, 3, 4, 5]
    >>> sort_array([-2, -3, -4, -5, -6]) == [-6, -5, -4, -3, -2]
    >>> sort_array([1, 0, 2, 3, 4]) [0, 1, 2, 3, 4]
    """

def sort_array(arr):
    """Sort an array of integers based on the number of 1s in their binary representation
    in ascending order. For ties, sort by the integer value ascending.
    >>> sort_array([1, 5, 2, 3, 4]) == [1, 2, 3, 4, 5]
    >>> sort_array([-2, -3, -4, -5, -6]) == [-6, -5, -4, -3, -2]
    >>> sort_array([1, 0, 2, 3, 4]) [0, 1, 2, 3, 4]
    """

Answer: return sorted(sorted(arr), key=lambda x: bin(x)[2:].count('1'))

def check(candidate):

    # Check some simple cases
    assert True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1,5,2,3,4]) == [1, 2, 4, 3, 5]
    assert candidate([-2,-3,-4,-5,-6]) == [-4, -2, -6, -5, -3]
    assert candidate([1,0,2,3,4]) == [0, 1, 2, 4, 3]
    assert candidate([]) == []
    assert candidate([2,5,77,4,5,3,5,7,2,3,4]) == [2, 2, 4, 4, 3, 3, 5, 5, 5, 7, 77]
    assert candidate([3,6,44,12,32,5]) == [32, 3, 5, 6, 12, 44]
    assert candidate([2,4,8,16,32]) == [2, 4, 8, 16, 32]
    assert candidate([2,4,8,16,32]) == [2, 4, 8, 16, 32]

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def select_words(s, n):
    """Given a string s and a natural number n, you have been tasked to implement
    a function that returns a list of all words from string s that contain exactly
    n consonants, in order these words appear in the string s.
    If the string s is empty then the function should return an empty list.
    Note: you may assume the input string contains only letters and spaces.
    Examples:
    select_words("Mary had a little lamb", 4) ==> ["little"]
    select_words("Mary had a little lamb", 3) ==> ["Mary", "lamb"]
    select_words("simple white space", 2) ==> []
    select_words("Hello world", 4) ==> ["world"]
    select_words("Uncle sam", 3) ==> ["Uncle"]
    """

def select_words(s, n):
    """From the given string s, extract all words that contain exactly n consonants
    (letters other than vowels). Return them in the order they appear.
    If s is empty, return empty list.
    Examples:
    select_words("Mary had a little lamb", 4) ==> ["little"]
    select_words("Mary had a little lamb", 3) ==> ["Mary", "lamb"]
    select_words("simple white space", 2) ==> []
    select_words("Hello world", 4) ==> ["world"]
    select_words("Uncle sam", 3) ==> ["Uncle"]
    """

Answer:
    result = []
    for word in s.split():
        n_consonants = 0
        for i in range(0, len(word)):
            if word[i].lower() not in ["a","e","i","o","u"]:
                n_consonants += 1
        if n_consonants == n:
            result.append(word)
    return result

def check(candidate):

    # Check some simple cases
    assert candidate("Mary had a little lamb", 4) == ["little"], "First test error: " + str(candidate("Mary had a little lamb", 4))
    assert candidate("Mary had a little lamb", 3) == ["Mary", "lamb"], "Second test error: " + str(candidate("Mary had a little lamb", 3))
    assert candidate("simple white space", 2) == [], "Third test error: " + str(candidate("simple white space", 2))
    assert candidate("Hello world", 4) == ["world"], "Fourth test error: " + str(candidate("Hello world", 4))
    assert candidate("Uncle sam", 3) == ["Uncle"], "Fifth test error: " + str(candidate("Uncle sam", 3))

    # Check some edge cases that are easy to work out by hand.
    assert candidate("", 4) == [], "1st edge test error: " + str(candidate("", 4))
    assert candidate("a b c d e f", 1) == ["b", "c", "d", "f"], "2nd edge test error: " + str(candidate("a b c d e f", 1))


def get_closest_vowel(word):
    """You are given a word. Your task is to find the closest vowel that stands between
    two consonants from the right side of the word (case sensitive).

    Vowels in the beginning and ending doesn't count. Return empty string if you didn't
    find any vowel met the above condition.

    You may assume that the given string contains English letter only.

    Example:
    get_closest_vowel("yogurt") ==> "u"
    get_closest_vowel("FULL") ==> "U"
    get_closest_vowel("quick") ==> ""
    get_closest_vowel("ab") ==> ""
    """

def get_closest_vowel(word):
    """Find the rightmost vowel in the word that is immediately surrounded by consonants
    (i.e., has a consonant on both sides) when scanning from the right.
    Vowels at the beginning or end are ignored. Return that vowel, or an empty string if none.
    Example:
    get_closest_vowel("yogurt") ==> "u"
    get_closest_vowel("FULL") ==> "U"
    get_closest_vowel("quick") ==> ""
    get_closest_vowel("ab") ==> ""
    """

Answer:
    if len(word) < 3:
        return ""

    vowels = {"a", "e", "i", "o", "u", "A", "E", 'O', 'U', 'I'}
    for i in range(len(word)-2, 0, -1):
        if word[i] in vowels:
            if (word[i+1] not in vowels) and (word[i-1] not in vowels):
                return word[i]
    return ""

def check(candidate):

    # Check some simple cases
    assert candidate("yogurt") == "u"
    assert candidate("full") == "u"
    assert candidate("easy") == ""
    assert candidate("eAsy") == ""
    assert candidate("ali") == ""
    assert candidate("bad") == "a"
    assert candidate("most") == "o"
    assert candidate("ab") == ""
    assert candidate("ba") == ""
    assert candidate("quick") == ""
    assert candidate("anime") == "i"
    assert candidate("Asia") == ""
    assert candidate("Above") == "o"

    # Check some edge cases that are easy to work out by hand.
    assert True


def match_parens(lst):
    '''
    You are given a list of two strings, both strings consist of open
    parentheses '(' or close parentheses ')' only.
    Your job is to check if it is possible to concatenate the two strings in
    some order, that the resulting string will be good.
    A string S is considered to be good if and only if all parentheses in S
    are balanced. For example: the string '(())()' is good, while the string
    '())' is not.
    Return 'Yes' if there's a way to make a good string, and return 'No' otherwise.

    Examples:
    match_parens(['()(', ')']) == 'Yes'
    match_parens([')', ')']) == 'No'
    '''

def match_parens(lst):
    """Given a list of two strings, each consisting only of '(' and ')',
    determine if it's possible to concatenate them in some order to form a
    string with balanced parentheses. Return 'Yes' if possible, else 'No'.
    Examples:
    match_parens(['()(', ')']) == 'Yes'
    match_parens([')', ')']) == 'No'
    """

Answer:
    def check(s):
        val = 0
        for i in s:
            if i == '(':
                val = val + 1
            else:
                val = val - 1
            if val < 0:
                return False
        return True if val == 0 else False

    S1 = lst[0] + lst[1]
    S2 = lst[1] + lst[0]
    return 'Yes' if check(S1) or check(S2) else 'No'

def check(candidate):

    # Check some simple cases
    assert candidate(['()(', ')']) == 'Yes'
    assert candidate([')', ')']) == 'No'
    assert candidate(['(()(())', '())())']) == 'No'
    assert candidate([')())', '(()()(']) == 'Yes'
    assert candidate(['(())))', '(()())((']) == 'Yes'
    assert candidate(['()', '())']) == 'No'
    assert candidate(['(()(', '()))()']) == 'Yes'
    assert candidate(['((((', '((())']) == 'No'
    assert candidate([')(()', '(()(']) == 'No'
    assert candidate([')(', ')(']) == 'No'

    # Check some edge cases that are easy to work out by hand.
    assert candidate(['(', ')']) == 'Yes'
    assert candidate([')', '(']) == 'Yes'


def maximum(arr, k):
    """
    Given an array arr of integers and a positive integer k, return a sorted list
    of length k with the maximum k numbers in arr.

    Example 1:

        Input: arr = [-3, -4, 5], k = 3
        Output: [-4, -3, 5]

    Example 2:

        Input: arr = [4, -4, 4], k = 2
        Output: [4, 4]

    Example 3:

        Input: arr = [-3, 2, 1, 2, -1, -2, 1], k = 1
        Output: [2]

    Note:
        1. The length of the array will be in the range of [1, 1000].
        2. The elements in the array will be in the range of [-1000, 1000].
        3. 0 <= k <= len(arr)
    """

def maximum(arr, k):
    """Return a sorted list of the k largest elements from arr, in ascending order.
    If k=0, return empty list.
    Example 1:
        Input: arr = [-3, -4, 5], k = 3
        Output: [-4, -3, 5]
    Example 2:
        Input: arr = [4, -4, 4], k = 2
        Output: [4, 4]
    Example 3:
        Input: arr = [-3, 2, 1, 2, -1, -2, 1], k = 1
        Output: [2]
    Note:
        1. The length of the array will be in the range of [1, 1000].
        2. The elements in the array will be in the range of [-1000, 1000].
        3. 0 <= k <= len(arr)
    """

Answer:
    if k == 0:
        return []
    arr.sort()
    ans = arr[-k:]
    return ans


def solution(lst):
    """Given a non-empty list of integers, return the sum of all of the odd elements that are in even positions.

    Examples
    solution([5, 8, 7, 1]) ==> 12
    solution([3, 3, 3, 3, 3]) ==> 9
    solution([30, 13, 24, 321]) ==>0
    """

def solution(lst):
    """Given a non-empty list of integers, sum all elements that are both odd in value
    and located at even indices (0-based).
    Examples
    solution([5, 8, 7, 1]) ==> 12
    solution([3, 3, 3, 3, 3]) ==> 9
    solution([30, 13, 24, 321]) ==>0
    """

Answer: return sum([x for idx, x in enumerate(lst) if idx%2==0 and x%2==1])

def check(candidate):

    # Check some simple cases
    assert candidate([5, 8, 7, 1])    == 12
    assert candidate([3, 3, 3, 3, 3]) == 9
    assert candidate([30, 13, 24, 321]) == 0
    assert candidate([5, 9]) == 5
    assert candidate([2, 4, 8]) == 0
    assert candidate([30, 13, 23, 32]) == 23
    assert candidate([3, 13, 2, 9]) == 3

    # Check some edge cases that are easy to work out by hand.


def add_elements(arr, k):
    """
    Given a non-empty array of integers arr and an integer k, return
    the sum of the elements with at most two digits from the first k elements of arr.

    Example:

        Input: arr = [111,21,3,4000,5,6,7,8,9], k = 4
        Output: 24 # sum of 21 + 3

    Constraints:
        1. 1 <= len(arr) <= 100
        2. 1 <= k <= len(arr)
    """

def add_elements(arr, k):
    """Among the first k elements of arr, sum only those elements that have at most
    two decimal digits (i.e., absolute value < 100). Return the sum.
    Example:
        Input: arr = [111,21,3,4000,5,6,7,8,9], k = 4
        Output: 24 # sum of 21 + 3
    Constraints:
        1. 1 <= len(arr) <= 100
        2. 1 <= k <= len(arr)
    """

Answer: return sum(elem for elem in arr[:k] if len(str(elem)) <= 2)

def check(candidate):

    # Check some simple cases
    assert candidate([1,-2,-3,41,57,76,87,88,99], 3) == -4
    assert candidate([111,121,3,4000,5,6], 2) == 0
    assert candidate([11,21,3,90,5,6,7,8,9], 4) == 125
    assert candidate([111,21,3,4000,5,6,7,8,9], 4) == 24, "This prints if this assert fails 1 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate([1], 1) == 1, "This prints if this assert fails 2 (also good for debugging!)"


def get_odd_collatz(n):
    """
    Given a positive integer n, return a sorted list that has the odd numbers in collatz sequence.

    The Collatz conjecture is a conjecture in mathematics that concerns a sequence defined
    as follows: start with any positive integer n. Then each term is obtained from the
    previous term as follows: if the previous term is even, the next term is one half of
    the previous term. If the previous term is odd, the next term is 3 times the previous
    term plus 1. The conjecture is that no matter what value of n, the sequence will always reach 1.

    Note:
        1. Collatz(1) is [1].
        2. returned list sorted in increasing order.

    For example:
    get_odd_collatz(5) returns [1, 5] # The collatz sequence for 5 is [5, 16, 8, 4, 2, 1], so the odd numbers are only 1, and 5.
    """

def get_odd_collatz(n):
    """Generate the Collatz sequence starting from n, then extract all odd numbers
    from that sequence, and return them sorted in increasing order.
    Note: Collatz(1) is [1].
    For example:
    get_odd_collatz(5) returns [1, 5] # The collatz sequence for 5 is [5, 16, 8, 4, 2, 1], so the odd numbers are only 1, and 5.
    """

Answer:
    if n%2==0:
        odd_collatz = []
    else:
        odd_collatz = [n]
    while n > 1:
        if n % 2 == 0:
            n = n/2
        else:
            n = n*3 + 1

        if n%2 == 1:
            odd_collatz.append(int(n))

    return sorted(odd_collatz)

def check(candidate):

    # Check some simple cases
    assert candidate(14) == [1, 5, 7, 11, 13, 17]
    assert candidate(5) == [1, 5]
    assert candidate(12) == [1, 3, 5], "This prints if this assert fails 1 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate(1) == [1], "This prints if this assert fails 2 (also good for debugging!)"


def valid_date(date):
    """You have to write a function which validates a given date string and
    returns True if the date is valid otherwise False.
    The date is valid if all of the following rules are satisfied:
    1. The date string is not empty.
    2. The number of days is not less than 1 or higher than 31 days for months 1,3,5,7,8,10,12. And the number of days is not less than 1 or higher than 30 days for months 4,6,9,11. And, the number of days is not less than 1 or higher than 29 for the month 2.
    3. The months should not be less than 1 or higher than 12.
    4. The date should be in the format: mm-dd-yyyy

    for example:
    valid_date('03-11-2000') => True

    valid_date('15-01-2012') => False

    valid_date('04-0-2040') => False

    valid_date('06-04-2020') => True

    valid_date('06/04/2020') => False
    """

def valid_date(date):
    """Validate a date string in the format mm-dd-yyyy according to the following rules:
    1. String must not be empty.
    2. Month between 1-12.
    3. Day appropriate for the month (1-31 for months 1,3,5,7,8,10,12; 1-30 for 4,6,9,11; 1-29 for February).
    4. Must follow mm-dd-yyyy exactly.
    Return True if valid, else False.
    for example:
    valid_date('03-11-2000') => True
    valid_date('15-01-2012') => False
    valid_date('04-0-2040') => False
    valid_date('06-04-2020') => True
    valid_date('06/04/2020') => False
    """

Answer:
    try:
        date = date.strip()
        month, day, year = date.split('-')
        month, day, year = int(month), int(day), int(year)
        if month < 1 or month > 12:
            return False
        if month in [1,3,5,7,8,10,12] and day < 1 or day > 31:
            return False
        if month in [4,6,9,11] and day < 1 or day > 30:
            return False
        if month == 2 and day < 1 or day > 29:
            return False
    except:
        return False

    return True

def check(candidate):

    # Check some simple cases
    assert candidate('03-11-2000') == True

    assert candidate('15-01-2012') == False

    assert candidate('04-0-2040') == False

    assert candidate('06-04-2020') == True

    assert candidate('01-01-2007') == True

    assert candidate('03-32-2011') == False

    assert candidate('') == False

    assert candidate('04-31-3000') == False

    assert candidate('06-06-2005') == True

    assert candidate('21-31-2000') == False

    assert candidate('04-12-2003') == True

    assert candidate('04122003') == False

    assert candidate('20030412') == False

    assert candidate('2003-04') == False

    assert candidate('2003-04-12') == False

    assert candidate('04-2003') == False


def split_words(txt):
    '''
    Given a string of words, return a list of words split on whitespace, if no whitespaces exists in the text you
    should split on commas ',' if no commas exists you should return the number of lower-case letters with odd order in the
    alphabet, ord('a') = 0, ord('b') = 1, ... ord('z') = 25
    Examples
    split_words("Hello world!") ➞ ["Hello", "world!"]
    split_words("Hello,world!") ➞ ["Hello", "world!"]
    split_words("abcdef") == 3
    '''

def split_words(txt):
    '''Split the input string into words based on whitespace. If no whitespace exists,
    split on commas ','. If no commas exist either, count the number of lowercase letters
    whose alphabetical order is odd (a=0, b=1, ... z=25) and return that count.
    Examples
    split_words("Hello world!") ➞ ["Hello", "world!"]
    split_words("Hello,world!") ➞ ["Hello", "world!"]
    split_words("abcdef") == 3
    '''

Answer:
    if " " in txt:
        return txt.split()
    elif "," in txt:
        return txt.replace(',',' ').split()
    else:
        return len([i for i in txt if i.islower() and ord(i)%2 == 0])

def check(candidate):

    assert candidate("Hello world!") == ["Hello","world!"]
    assert candidate("Hello,world!") == ["Hello","world!"]
    assert candidate("Hello world,!") == ["Hello","world,!"]
    assert candidate("Hello,Hello,world !") == ["Hello,Hello,world","!"]
    assert candidate("abcdef") == 3
    assert candidate("aaabb") == 2
    assert candidate("aaaBb") == 1
    assert candidate("") == 0


def is_sorted(lst):
    '''
    Given a list of numbers, return whether or not they are sorted
    in ascending order. If list has more than 1 duplicate of the same
    number, return False. Assume no negative numbers and only integers.

    Examples
    is_sorted([5]) ➞ True
    is_sorted([1, 2, 3, 4, 5]) ➞ True
    is_sorted([1, 3, 2, 4, 5]) ➞ False
    is_sorted([1, 2, 3, 4, 5, 6]) ➞ True
    is_sorted([1, 2, 3, 4, 5, 6, 7]) ➞ True
    is_sorted([1, 3, 2, 4, 5, 6, 7]) ➞ False
    is_sorted([1, 2, 2, 3, 3, 4]) ➞ True
    is_sorted([1, 2, 2, 2, 3, 4]) ➞ False
    '''

def is_sorted(lst):
    '''Check if the list is sorted in non-decreasing order. Additionally, if any number
    appears more than once, that's allowed only if it appears exactly twice? Actually the original says: "If list has more than 1 duplicate of the same number, return False." So it means if any number appears 3 or more times, return False. Otherwise, if sorted and no number appears >2 times, return True.
    For example:
    is_sorted([5]) ➞ True
    is_sorted([1, 2, 3, 4, 5]) ➞ True
    is_sorted([1, 3, 2, 4, 5]) ➞ False
    is_sorted([1, 2, 3, 4, 5, 6]) ➞ True
    is_sorted([1, 2, 3, 4, 5, 6, 7]) ➞ True
    is_sorted([1, 3, 2, 4, 5, 6, 7]) ➞ False
    is_sorted([1, 2, 2, 3, 3, 4]) ➞ True
    is_sorted([1, 2, 2, 2, 3, 4]) ➞ False
    '''

Answer:
    count_digit = dict([(i, 0) for i in lst])
    for i in lst:
        count_digit[i]+=1
    if any(count_digit[i] > 2 for i in lst):
        return False
    if all(lst[i-1] <= lst[i] for i in range(1, len(lst))):
        return True
    else:
        return False

def check(candidate):

    # Check some simple cases
    assert candidate([5]) == True
    assert candidate([1, 2, 3, 4, 5]) == True
    assert candidate([1, 3, 2, 4, 5]) == False
    assert candidate([1, 2, 3, 4, 5, 6]) == True
    assert candidate([1, 2, 3, 4, 5, 6, 7]) == True
    assert candidate([1, 3, 2, 4, 5, 6, 7]) == False, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([]) == True, "This prints if this assert fails 2 (good for debugging!)"
    assert candidate([1]) == True, "This prints if this assert fails 3 (good for debugging!)"
    assert candidate([3, 2, 1]) == False, "This prints if this assert fails 4 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate([1, 2, 2, 2, 3, 4]) == False, "This prints if this assert fails 5 (good for debugging!)"
    assert candidate([1, 2, 3, 3, 3, 4]) == False, "This prints if this assert fails 6 (good for debugging!)"
    assert candidate([1, 2, 2, 3, 3, 4]) == True, "This prints if this assert fails 7 (good for debugging!)"
    assert candidate([1, 2, 3, 4]) == True, "This prints if this assert fails 8 (good for debugging!)"


def intersection(interval1, interval2):
    """You are given two intervals,
    where each interval is a pair of integers. For example, interval = (start, end) = (1, 2).
    The given intervals are closed which means that the interval (start, end)
    includes both start and end.
    For each given interval, it is assumed that its start is less or equal its end.
    Your task is to determine whether the length of intersection of these two
    intervals is a prime number.
    Example, the intersection of the intervals (1, 3), (2, 4) is (2, 3)
    which its length is 1, which not a prime number.
    If the length of the intersection is a prime number, return "YES",
    otherwise, return "NO".
    If the two intervals don't intersect, return "NO".

    [input/output] samples:
    intersection((1, 2), (2, 3)) ==> "NO"
    intersection((-1, 1), (0, 4)) ==> "NO"
    intersection((-3, -1), (-5, 5)) ==> "YES"
    """

def intersection(interval1, interval2):
    """Given two closed intervals (each a pair of integers), compute the length of
    their intersection (number of integers overlapping). If the length is a prime number,
    return "YES", otherwise "NO". If intervals do not intersect, return "NO".
    [input/output] samples:
    intersection((1, 2), (2, 3)) ==> "NO"
    intersection((-1, 1), (0, 4)) ==> "NO"
    intersection((-3, -1), (-5, 5)) ==> "YES"
    """

Answer:
    def is_prime(num):
        if num == 1 or num == 0:
            return False
        if num == 2:
            return True
        for i in range(2, num):
            if num%i == 0:
                return False
        return True

    l = max(interval1[0], interval2[0])
    r = min(interval1[1], interval2[1])
    length = r - l
    if length > 0 and is_prime(length):
        return "YES"
    return "NO"

def check(candidate):

    # Check some simple cases
    assert candidate((1, 2), (2, 3)) == "NO"
    assert candidate((-1, 1), (0, 4)) == "NO"
    assert candidate((-3, -1), (-5, 5)) == "YES"
    assert candidate((-2, 2), (-4, 0)) == "YES"

    # Check some edge cases that are easy to work out by hand.
    assert candidate((-11, 2), (-1, -1)) == "NO"
    assert candidate((1, 2), (3, 5)) == "NO"
    assert candidate((1, 2), (1, 2)) == "NO"
    assert candidate((-2, -2), (-3, -2)) == "NO"


def prod_signs(arr):
    """
    You are given an array arr of integers and you need to return
    sum of magnitudes of integers multiplied by product of all signs
    of each number in the array, represented by 1, -1 or 0.
    Note: return None for empty arr.

    Example:
    >>> prod_signs([1, 2, 2, -4]) == -9
    >>> prod_signs([0, 1]) == 0
    >>> prod_signs([]) == None
    """

def prod_signs(arr):
    """Compute the sum of absolute values of all integers in arr, multiplied by
    the product of their signs (each sign is -1, 0, or 1). Return None if arr is empty.
    Example:
    >>> prod_signs([1, 2, 2, -4]) == -9
    >>> prod_signs([0, 1]) == 0
    >>> prod_signs([]) == None
    """

Answer:
    if not arr: return None
    prod = 0 if 0 in arr else (-1) ** len(list(filter(lambda x: x < 0, arr)))
    return prod * sum([abs(i) for i in arr])

def check(candidate):

    # Check some simple cases
    assert True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1, 2, 2, -4]) == -9
    assert candidate([0, 1]) == 0
    assert candidate([1, 1, 1, 2, 3, -1, 1]) == -10
    assert candidate([]) == None
    assert candidate([2, 4,1, 2, -1, -1, 9]) == 20
    assert candidate([-1, 1, -1, 1]) == 4
    assert candidate([-1, 1, 1, 1]) == -4
    assert candidate([-1, 1, 1, 0]) == 0

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def minPath(grid, k):
    """
    Given a grid with N rows and N columns (N >= 2) and a positive integer k,
    each cell of the grid contains a value. Every integer in the range [1, N * N]
    inclusive appears exactly once on the cells of the grid.

    You have to find the minimum path of length k in the grid. You can start
    from any cell, and in each step you can move to any of the neighbor cells,
    in other words, you can go to cells which share an edge with you current
    cell.
    Please note that a path of length k means visiting exactly k cells (not
    necessarily distinct).
    You CANNOT go off the grid.
    A path A (of length k) is considered less than a path B (of length k) if
    after making the ordered lists of the values on the cells that A and B go
    through (let's call them lst_A and lst_B), lst_A is lexicographically less
    than lst_B, in other words, there exist an integer index i (1 <= i <= k)
    such that lst_A[i] < lst_B[i] and for any j (1 <= j < i) we have
    lst_A[j] = lst_B[j].
    It is guaranteed that the answer is unique.
    Return an ordered list of the values on the cells that the minimum path go through.

    Examples:

        Input: grid = [ [1,2,3], [4,5,6], [7,8,9]], k = 3
        Output: [1, 2, 1]

        Input: grid = [ [5,9,3], [4,1,6], [7,8,2]], k = 1
        Output: [1]
    """

def minPath(grid, k):
    """Find the lexicographically smallest path of length k in a grid where each cell
    contains a unique integer from 1 to N*N. You can start anywhere and move to adjacent
    cells (sharing an edge). The path is a sequence of k cell values. Return that sequence.
    It is guaranteed that the answer is unique.
    Examples:
        Input: grid = [ [1,2,3], [4,5,6], [7,8,9]], k = 3
        Output: [1, 2, 1]
        Input: grid = [ [5,9,3], [4,1,6], [7,8,2]], k = 1
        Output: [1]
    """

Answer:
    n = len(grid)
    val = n * n + 1
    for i in range(n):
        for j in range(n):
            if grid[i][j] == 1:
                temp = []
                if i != 0:
                    temp.append(grid[i - 1][j])

                if j != 0:
                    temp.append(grid[i][j - 1])

                if i != n - 1:
                    temp.append(grid[i + 1][j])

                if j != n - 1:
                    temp.append(grid[i][j + 1])

                val = min(temp)

    ans = []
    for i in range(k):
        if i % 2 == 0:
            ans.append(1)
        else:
            ans.append(val)
    return ans


def tri(n):
    """Everyone knows Fibonacci sequence, it was studied deeply by mathematicians in
    the last couple centuries. However, what people don't know is Tribonacci sequence.
    Tribonacci sequence is defined by the recurrence:
    tri(1) = 3
    tri(n) = 1 + n / 2, if n is even.
    tri(n) =  tri(n - 1) + tri(n - 2) + tri(n + 1), if n is odd.
    For example:
    tri(2) = 1 + (2 / 2) = 2
    tri(4) = 3
    tri(3) = tri(2) + tri(1) + tri(4)
           = 2 + 3 + 3 = 8
    You are given a non-negative integer number n, you have to a return a list of the
    first n + 1 numbers of the Tribonacci sequence.
    Examples:
    tri(3) = [1, 3, 2, 8]
    """

def tri(n):
    """Implement a function that returns the list of the first n+1 terms of the Tribonacci sequence defined as: tri(0)=1, tri(1)=3, for even n>0: tri(n) = 1 + n/2, for odd n>1: tri(n) = tri(n-1)+tri(n-2)+tri(n+1). Include examples.
    Examples:
    tri(3) = [1, 3, 2, 8]
    """

Answer:
    if n == 0:
        return [1]
    my_tri = [1, 3]
    for i in range(2, n + 1):
        if i % 2 == 0:
            my_tri.append(i / 2 + 1)
        else:
            my_tri.append(my_tri[i - 1] + my_tri[i - 2] + (i + 3) / 2)
    return my_tri


def digits(n):
    """Given a positive integer n, return the product of the odd digits.
    Return 0 if all digits are even.
    For example:
    digits(1)  == 1
    digits(4)  == 0
    digits(235) == 15
    """

def digits(n):
    """Given a positive integer n, compute the product of all its odd digits.
    If there are no odd digits, return 0.
    For example:
    digits(1)  == 1
    digits(4)  == 0
    digits(235) == 15
    """

Answer:
    product = 1
    odd_count = 0
    for digit in str(n):
        int_digit = int(digit)
        if int_digit%2 == 1:
            product= product*int_digit
            odd_count+=1
    if odd_count ==0:
        return 0
    else:
        return product

def check(candidate):

    # Check some simple cases
    assert candidate(5) == 5
    assert candidate(54) == 5
    assert candidate(120) ==1
    assert candidate(5014) == 5
    assert candidate(98765) == 315
    assert candidate(5576543) == 2625

    # Check some edge cases that are easy to work out by hand.
    assert candidate(2468) == 0


def is_nested(string):
    '''
    Create a function that takes a string as input which contains only square brackets.
    The function should return True if and only if there is a valid subsequence of brackets
    where at least one bracket in the subsequence is nested.

    is_nested('[[]]') ➞ True
    is_nested('[]]]]]]][[[[[]') ➞ False
    is_nested('[][]') ➞ False
    is_nested('[]') ➞ False
    is_nested('[[][]]') ➞ True
    is_nested('[[]][[') ➞ True
    '''

def is_nested(string):
    '''Determine if the given string of brackets contains a valid subsequence
    that has at least one nested bracket pair. A nested pair means an opening
    bracket that is not immediately closed.
    is_nested('[[]]') ➞ True
    is_nested('[]]]]]]][[[[[]') ➞ False
    is_nested('[][]') ➞ False
    is_nested('[]') ➞ False
    is_nested('[[][]]') ➞ True
    is_nested('[[]][[') ➞ True
    '''

Answer:
    opening_bracket_index = []
    closing_bracket_index = []
    for i in range(len(string)):
        if string[i] == '[':
            opening_bracket_index.append(i)
        else:
            closing_bracket_index.append(i)
    closing_bracket_index.reverse()
    cnt = 0
    i = 0
    l = len(closing_bracket_index)
    for idx in opening_bracket_index:
        if i < l and idx < closing_bracket_index[i]:
            cnt += 1
            i += 1
    return cnt >= 2

def check(candidate):

    # Check some simple cases
    assert candidate('[[]]') == True, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate('[]]]]]]][[[[[]') == False
    assert candidate('[][]') == False
    assert candidate(('[]')) == False
    assert candidate('[[[[]]]]') == True
    assert candidate('[]]]]]]]]]]') == False
    assert candidate('[][][[]]') == True
    assert candidate('[[]') == False
    assert candidate('[]]') == False
    assert candidate('[[]][[') == True
    assert candidate('[[][]]') == True

    # Check some edge cases that are easy to work out by hand.
    assert candidate('') == False, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate('[[[[[[[[') == False
    assert candidate(']]]]]]]]') == False


def sum_squares(lst):
    """You are given a list of numbers.
    You need to return the sum of squared numbers in the given list,
    round each element in the list to the upper int(Ceiling) first.
    Examples:
    For lst = [1,2,3] the output should be 14
    For lst = [1,4,9] the output should be 98
    For lst = [1,3,5,7] the output should be 84
    For lst = [1.4,4.2,0] the output should be 29
    For lst = [-2.4,1,1] the output should be 6

    """

def sum_squares(lst):
    """Given a list of numbers, round each element up to the nearest integer (ceiling),
    then compute the sum of their squares.
    Examples:
    For lst = [1,2,3] the output should be 14
    For lst = [1,4,9] the output should be 98
    For lst = [1,3,5,7] the output should be 84
    For lst = [1.4,4.2,0] the output should be 29
    For lst = [-2.4,1,1] the output should be 6
    """

Answer:
    import math
    squared = 0
    for i in lst:
        squared += math.ceil(i)**2
    return squared

def check(candidate):

    # Check some simple cases
    assert candidate([1,2,3])==14, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1.0,2,3])==14, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1,3,5,7])==84, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1.4,4.2,0])==29, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([-2.4,1,1])==6, "This prints if this assert fails 1 (good for debugging!)"

    assert candidate([100,1,15,2])==10230, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([10000,10000])==200000000, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([-1.4,4.6,6.3])==75, "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([-1.4,17.9,18.9,19.9])==1086, "This prints if this assert fails 1 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate([0])==0, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([-1])==1, "This prints if this assert fails 2 (also good for debugging!)"
    assert candidate([-1,1,0])==2, "This prints if this assert fails 2 (also good for debugging!)"


def check_if_last_char_is_a_letter(txt):
    '''
    Create a function that returns True if the last character
    of a given string is an alphabetical character and is not
    a part of a word, and False otherwise.
    Note: "word" is a group of characters separated by space.

    Examples:
    check_if_last_char_is_a_letter("apple pie") ➞ False
    check_if_last_char_is_a_letter("apple pi e") ➞ True
    check_if_last_char_is_a_letter("apple pi e ") ➞ False
    check_if_last_char_is_a_letter("") ➞ False
    '''

def check_if_last_char_is_a_letter(txt):
    '''Return True if the final character of the string is an alphabetic letter
    and that character is not part of a multi-character word (i.e., it is a standalone
    letter separated by spaces). Otherwise False.
    Examples:
    check_if_last_char_is_a_letter("apple pie") ➞ False
    check_if_last_char_is_a_letter("apple pi e") ➞ True
    check_if_last_char_is_a_letter("apple pi e ") ➞ False
    check_if_last_char_is_a_letter("") ➞ False
    '''

Answer:
    check = txt.split(' ')[-1]
    return True if len(check) == 1 and (97 <= ord(check.lower()) <= 122) else False

def check(candidate):

    # Check some simple cases
    assert candidate("apple") == False
    assert candidate("apple pi e") == True
    assert candidate("eeeee") == False
    assert candidate("A") == True
    assert candidate("Pumpkin pie ") == False
    assert candidate("Pumpkin pie 1") == False
    assert candidate("") == False
    assert candidate("eeeee e ") == False
    assert candidate("apple pie") == False
    assert candidate("apple pi e ") == False

    # Check some edge cases that are easy to work out by hand.
    assert True


def can_arrange(arr):
    """Create a function which returns the largest index of an element which
    is not greater than or equal to the element immediately preceding it. If
    no such element exists then return -1. The given array will not contain
    duplicate values.

    Examples:
    can_arrange([1,2,4,3,5]) = 3
    can_arrange([1,2,3]) = -1
    """

def can_arrange(arr):
    """Return the largest index i (0-based) such that arr[i] is less than arr[i-1]
    (i.e., the element is not greater than or equal to the preceding one).
    If no such index, return -1. The array has no duplicate values.
    Examples:
    can_arrange([1,2,4,3,5]) = 3
    can_arrange([1,2,3]) = -1
    """

Answer:
    ind=-1
    i=1
    while i<len(arr):
      if arr[i]<arr[i-1]:
        ind=i
      i+=1
    return ind

def check(candidate):

    # Check some simple cases
    assert candidate([1,2,4,3,5])==3
    assert candidate([1,2,4,5])==-1
    assert candidate([1,4,2,5,6,7,8,9,10])==2
    assert candidate([4,8,5,7,3])==4

    # Check some edge cases that are easy to work out by hand.
    assert candidate([])==-1


def largest_smallest_integers(lst):
    '''
    Create a function that returns a tuple (a, b), where 'a' is
    the largest of negative integers, and 'b' is the smallest
    of positive integers in a list.
    If there is no negative or positive integers, return them as None.

    Examples:
    largest_smallest_integers([2, 4, 1, 3, 5, 7]) == (None, 1)
    largest_smallest_integers([]) == (None, None)
    largest_smallest_integers([0]) == (None, None)
    '''

def largest_smallest_integers(lst):
    '''Return a tuple (a, b) where a is the greatest negative integer in the list,
    and b is the smallest positive integer. If either category is missing, set that
    value to None.
    Examples:
    largest_smallest_integers([2, 4, 1, 3, 5, 7]) == (None, 1)
    largest_smallest_integers([]) == (None, None)
    largest_smallest_integers([0]) == (None, None)
    '''

Answer:
    smallest = list(filter(lambda x: x < 0, lst))
    largest = list(filter(lambda x: x > 0, lst))
    return (max(smallest) if smallest else None, min(largest) if largest else None)

def check(candidate):

    # Check some simple cases
    assert candidate([2, 4, 1, 3, 5, 7]) == (None, 1)
    assert candidate([2, 4, 1, 3, 5, 7, 0]) == (None, 1)
    assert candidate([1, 3, 2, 4, 5, 6, -2]) == (-2, 1)
    assert candidate([4, 5, 3, 6, 2, 7, -7]) == (-7, 2)
    assert candidate([7, 3, 8, 4, 9, 2, 5, -9]) == (-9, 2)
    assert candidate([]) == (None, None)
    assert candidate([0]) == (None, None)
    assert candidate([-1, -3, -5, -6]) == (-1, None)
    assert candidate([-1, -3, -5, -6, 0]) == (-1, None)
    assert candidate([-6, -4, -4, -3, 1]) == (-3, 1)
    assert candidate([-6, -4, -4, -3, -100, 1]) == (-3, 1)

    # Check some edge cases that are easy to work out by hand.
    assert True


def compare_one(a, b):
    """
    Create a function that takes integers, floats, or strings representing
    real numbers, and returns the larger variable in its given variable type.
    Return None if the values are equal.
    Note: If a real number is represented as a string, the floating point might be . or ,

    compare_one(1, 2.5) ➞ 2.5
    compare_one(1, "2,3") ➞ "2,3"
    compare_one("5,1", "6") ➞ "6"
    compare_one("1", 1) ➞ None
    """

def compare_one(a, b):
    """
    Compare two values that may be integers, floats, or strings representing
    real numbers (with possible comma as decimal separator). Return the larger
    value in its original type; if they are equal, return None.
    compare_one(1, 2.5) ➞ 2.5
    compare_one(1, "2,3") ➞ "2,3"
    compare_one("5,1", "6") ➞ "6"
    compare_one("1", 1) ➞ None
    """

Answer:
    temp_a, temp_b = a, b
    if isinstance(temp_a, str): temp_a = temp_a.replace(',','.')
    if isinstance(temp_b, str): temp_b = temp_b.replace(',','.')
    if float(temp_a) == float(temp_b): return None
    return a if float(temp_a) > float(temp_b) else b

def check(candidate):

    # Check some simple cases
    assert candidate(1, 2) == 2
    assert candidate(1, 2.5) == 2.5
    assert candidate(2, 3) == 3
    assert candidate(5, 6) == 6
    assert candidate(1, "2,3") == "2,3"
    assert candidate("5,1", "6") == "6"
    assert candidate("1", "2") == "2"
    assert candidate("1", 1) == None

    # Check some edge cases that are easy to work out by hand.
    assert True


def is_equal_to_sum_even(n):
    """Evaluate whether the given number n can be written as the sum of exactly 4 positive even numbers
    Example
    is_equal_to_sum_even(4) == False
    is_equal_to_sum_even(6) == False
    is_equal_to_sum_even(8) == True
    """

def is_equal_to_sum_even(n):
    """Determine if n can be expressed as the sum of exactly four positive even numbers.
    Example
    is_equal_to_sum_even(4) == False
    is_equal_to_sum_even(6) == False
    is_equal_to_sum_even(8) == True
    """

Answer: return n%2 == 0 and n >= 8

def check(candidate):
    assert candidate(4) == False
    assert candidate(6) == False
    assert candidate(8) == True
    assert candidate(10) == True
    assert candidate(11) == False
    assert candidate(12) == True
    assert candidate(13) == False
    assert candidate(16) == True


def special_factorial(n):
    """The Brazilian factorial is defined as:
    brazilian_factorial(n) = n! * (n-1)! * (n-2)! * ... * 1!
    where n > 0

    For example:
    >>> special_factorial(4)
    288

    The function will receive an integer as input and should return the special
    factorial of this integer.
    """

def special_factorial(n):
    """Compute the Brazilian factorial (also known as superfactorial) defined as
    n! * (n-1)! * ... * 1!.
    For example:
    >>> special_factorial(4)
    288
    """

Answer:
    fact_i = 1
    special_fact = 1
    for i in range(1, n+1):
        fact_i *= i
        special_fact *= fact_i
    return special_fact

def check(candidate):

    # Check some simple cases
    assert candidate(4) == 288, "Test 4"
    assert candidate(5) == 34560, "Test 5"
    assert candidate(7) == 125411328000, "Test 7"

    # Check some edge cases that are easy to work out by hand.
    assert candidate(1) == 1, "Test 1"


def fix_spaces(text):
    """
    Given a string text, replace all spaces in it with underscores,
    and if a string has more than 2 consecutive spaces,
    then replace all consecutive spaces with -

    fix_spaces("Example") == "Example"
    fix_spaces("Example 1") == "Example_1"
    fix_spaces(" Example 2") == "_Example_2"
    fix_spaces(" Example   3") == "_Example-3"
    """

def fix_spaces(text):
    """
    Replace every single space with an underscore, but if there are more than
    two consecutive spaces, replace that whole run with a single hyphen.
    fix_spaces("Example") == "Example"
    fix_spaces("Example 1") == "Example_1"
    fix_spaces(" Example 2") == "_Example_2"
    fix_spaces(" Example   3") == "_Example-3"
    """

Answer:
    new_text = ""
    i = 0
    start, end = 0, 0
    while i < len(text):
        if text[i] == " ":
            end += 1
        else:
            if end - start > 2:
                new_text += "-"+text[i]
            elif end - start > 0:
                new_text += "_"*(end - start)+text[i]
            else:
                new_text += text[i]
            start, end = i+1, i+1
        i+=1
    if end - start > 2:
        new_text += "-"
    elif end - start > 0:
        new_text += "_"
    return new_text

def check(candidate):

    # Check some simple cases
    assert candidate("Example") == "Example", "This prints if this assert fails 1 (good for debugging!)"
    assert candidate("Mudasir Hanif ") == "Mudasir_Hanif_", "This prints if this assert fails 2 (good for debugging!)"
    assert candidate("Yellow Yellow  Dirty  Fellow") == "Yellow_Yellow__Dirty__Fellow", "This prints if this assert fails 3 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate("Exa   mple") == "Exa-mple", "This prints if this assert fails 4 (good for debugging!)"
    assert candidate("   Exa 1 2 2 mple") == "-Exa_1_2_2_mple", "This prints if this assert fails 4 (good for debugging!)"


def file_name_check(file_name):
    """Create a function which takes a string representing a file's name, and returns
    'Yes' if the the file's name is valid, and returns 'No' otherwise.
    A file's name is considered to be valid if and only if all the following conditions
    are met:
    - There should not be more than three digits ('0'-'9') in the file's name.
    - The file's name contains exactly one dot '.'
    - The substring before the dot should not be empty, and it starts with a letter from
    the latin alphapet ('a'-'z' and 'A'-'Z').
    - The substring after the dot should be one of these: ['txt', 'exe', 'dll']
    Examples:
    file_name_check("example.txt") # => 'Yes'
    file_name_check("1example.dll") # => 'No' (the name should start with a latin alphapet letter)
    """

def file_name_check(file_name):
    """Check if the given file name string meets these criteria:
    1. Contains no more than three digits.
    2. Contains exactly one dot '.'.
    3. The part before the dot is non-empty and starts with a letter (a-z or A-Z).
    4. The part after the dot is one of: 'txt', 'exe', 'dll'.
    Return 'Yes' if valid, else 'No'.
    Examples:
    file_name_check("example.txt") # => 'Yes'
    file_name_check("1example.dll") # => 'No'
    """

Answer:
    suf = ['txt', 'exe', 'dll']
    lst = file_name.split(sep='.')
    if len(lst) != 2:
        return 'No'
    if not lst[1] in suf:
        return 'No'
    if len(lst[0]) == 0:
        return 'No'
    if not lst[0][0].isalpha():
        return 'No'
    t = len([x for x in lst[0] if x.isdigit()])
    if t > 3:
        return 'No'
    return 'Yes'

def check(candidate):

    # Check some simple cases
    assert candidate("example.txt") == 'Yes'
    assert candidate("1example.dll") == 'No'
    assert candidate('s1sdf3.asd') == 'No'
    assert candidate('K.dll') == 'Yes'
    assert candidate('MY16FILE3.exe') == 'Yes'
    assert candidate('His12FILE94.exe') == 'No'
    assert candidate('_Y.txt') == 'No'
    assert candidate('?aREYA.exe') == 'No'
    assert candidate('/this_is_valid.dll') == 'No'
    assert candidate('this_is_valid.wow') == 'No'
    assert candidate('this_is_valid.txt') == 'Yes'
    assert candidate('this_is_valid.txtexe') == 'No'
    assert candidate('#this2_i4s_5valid.ten') == 'No'
    assert candidate('@this1_is6_valid.exe') == 'No'
    assert candidate('this_is_12valid.6exe4.txt') == 'No'
    assert candidate('all.exe.txt') == 'No'
    assert candidate('I563_No.exe') == 'Yes'
    assert candidate('Is3youfault.txt') == 'Yes'
    assert candidate('no_one#knows.dll') == 'Yes'
    assert candidate('1I563_Yes3.exe') == 'No'
    assert candidate('I563_Yes3.txtt') == 'No'
    assert candidate('final..txt') == 'No'
    assert candidate('final132') == 'No'
    assert candidate('_f4indsartal132.') == 'No'

    # Check some edge cases that are easy to work out by hand.
    assert candidate('.txt') == 'No'
    assert candidate('s.') == 'No'


def sum_squares(lst):
    """"
    This function will take a list of integers. For all entries in the list, the function shall square the integer entry if its index is a
    multiple of 3 and will cube the integer entry if its index is a multiple of 4 and not a multiple of 3. The function will not
    change the entries in the list whose indexes are not a multiple of 3 or 4. The function shall then return the sum of all entries.

    Examples:
    For lst = [1,2,3] the output should be 6
    For lst = []  the output should be 0
    For lst = [-1,-5,2,-1,-5]  the output should be -126
    """

def sum_squares(lst):
    """"
    For each element in the list, if its index is a multiple of 3, square it;
    if its index is a multiple of 4 but not 3, cube it; otherwise leave it unchanged.
    Return the sum of the modified list.
    Examples:
    For lst = [1,2,3] the output should be 6
    For lst = []  the output should be 0
    For lst = [-1,-5,2,-1,-5]  the output should be -126
    """

Answer:
    result =[]
    for i in range(len(lst)):
        if i %3 == 0:
            result.append(lst[i]**2)
        elif i % 4 == 0 and i%3 != 0:
            result.append(lst[i]**3)
        else:
            result.append(lst[i])
    return sum(result)


def words_in_sentence(sentence):
    """
    You are given a string representing a sentence,
    the sentence contains some words separated by a space,
    and you have to return a string that contains the words from the original sentence,
    whose lengths are prime numbers,
    the order of the words in the new string should be the same as the original one.

    Example 1:
        Input: sentence = "This is a test"
        Output: "is"

    Example 2:
        Input: sentence = "lets go for swimming"
        Output: "go for"

    Constraints:
        * 1 <= len(sentence) <= 100
        * sentence contains only letters
    """

def words_in_sentence(sentence):
    """
    Given a sentence (space-separated words), filter out words whose lengths are
    not prime numbers, and return a string of the remaining words in original order.
    Example 1:
        Input: sentence = "This is a test"
        Output: "is"
    Example 2:
        Input: sentence = "lets go for swimming"
        Output: "go for"
    Constraints:
        * 1 <= len(sentence) <= 100
        * sentence contains only letters
    """

Answer:
    new_lst = []
    for word in sentence.split():
        flg = 0
        if len(word) == 1:
            flg = 1
        for i in range(2, len(word)):
            if len(word)%i == 0:
                flg = 1
        if flg == 0 or len(word) == 2:
            new_lst.append(word)
    return " ".join(new_lst)

def check(candidate):

    # Check some simple cases
    assert candidate("This is a test") == "is"
    assert candidate("lets go for swimming") == "go for"
    assert candidate("there is no place available here") == "there is no place"
    assert candidate("Hi I am Hussein") == "Hi am Hussein"
    assert candidate("go for it") == "go for it"

    # Check some edge cases that are easy to work out by hand.
    assert candidate("here") == ""
    assert candidate("here is") == "is"


def simplify(x, n):
    """Your task is to implement a function that will simplify the expression
    x * n. The function returns True if x * n evaluates to a whole number and False
    otherwise. Both x and n, are string representation of a fraction, and have the following format,
    <numerator>/<denominator> where both numerator and denominator are positive whole numbers.

    You can assume that x, and n are valid fractions, and do not have zero as denominator.

    simplify("1/5", "5/1") = True
    simplify("1/6", "2/1") = False
    simplify("7/10", "10/2") = False
    """

def simplify(x, n):
    """Given two fractions represented as strings "numerator/denominator",
    determine if their product (x * n) is a whole number (integer). Return True if so,
    else False.
    simplify("1/5", "5/1") = True
    simplify("1/6", "2/1") = False
    simplify("7/10", "10/2") = False
    """

Answer:
    a, b = x.split("/")
    c, d = n.split("/")
    numerator = int(a) * int(c)
    denom = int(b) * int(d)
    if (numerator/denom == int(numerator/denom)):
        return True
    return False

def check(candidate):

    # Check some simple cases
    assert candidate("1/5", "5/1") == True, 'test1'
    assert candidate("1/6", "2/1") == False, 'test2'
    assert candidate("5/1", "3/1") == True, 'test3'
    assert candidate("7/10", "10/2") == False, 'test4'
    assert candidate("2/10", "50/10") == True, 'test5'
    assert candidate("7/2", "4/2") == True, 'test6'
    assert candidate("11/6", "6/1") == True, 'test7'
    assert candidate("2/3", "5/2") == False, 'test8'
    assert candidate("5/2", "3/5") == False, 'test9'
    assert candidate("2/4", "8/4") == True, 'test10'

    # Check some edge cases that are easy to work out by hand.
    assert candidate("2/4", "4/2") == True, 'test11'
    assert candidate("1/5", "5/1") == True, 'test12'
    assert candidate("1/5", "1/5") == False, 'test13'


def order_by_points(nums):
    """
    Write a function which sorts the given list of integers
    in ascending order according to the sum of their digits.
    Note: if there are several items with similar sum of their digits,
    order them based on their index in original list.

    For example:
    >>> order_by_points([1, 11, -1, -11, -12]) == [-1, -11, 1, -12, 11]
    >>> order_by_points([]) == []
    """

def order_by_points(nums):
    """
    Sort the list of integers by the sum of their digits in ascending order.
    If two numbers have the same digit sum, preserve their original relative order
    (stable sort).
    For example:
    >>> order_by_points([1, 11, -1, -11, -12]) == [-1, -11, 1, -12, 11]
    >>> order_by_points([]) == []
    """

Answer:
    def digits_sum(n):
        neg = 1
        if n < 0: n, neg = -1 * n, -1
        n = [int(i) for i in str(n)]
        n[0] = n[0] * neg
        return sum(n)
    return sorted(nums, key=digits_sum)


def specialFilter(nums):
    """Write a function that takes an array of numbers as input and returns
    the number of elements in the array that are greater than 10 and both
    first and last digits of a number are odd (1, 3, 5, 7, 9).
    For example:
    specialFilter([15, -73, 14, -15]) => 1
    specialFilter([33, -2, -3, 45, 21, 109]) => 2
    """

def specialFilter(nums):
    """Count the numbers in the list that are greater than 10 and have both the
    first and last digit odd (1,3,5,7,9). Return the count.
    For example:
    specialFilter([15, -73, 14, -15]) => 1
    specialFilter([33, -2, -3, 45, 21, 109]) => 2
    """

Answer:
    count = 0
    for num in nums:
        if num > 10:
            odd_digits = (1, 3, 5, 7, 9)
            number_as_string = str(num)
            if int(number_as_string[0]) in odd_digits and int(number_as_string[-1]) in odd_digits:
                count += 1

    return count

def check(candidate):

    # Check some simple cases
    assert candidate([5, -2, 1, -5]) == 0
    assert candidate([15, -73, 14, -15]) == 1
    assert candidate([33, -2, -3, 45, 21, 109]) == 2
    assert candidate([43, -12, 93, 125, 121, 109]) == 4
    assert candidate([71, -2, -33, 75, 21, 19]) == 3

    # Check some edge cases that are easy to work out by hand.
    assert candidate([1]) == 0
    assert candidate([]) == 0


def get_max_triples(n):
    """
    You are given a positive integer n. You have to create an integer array a of length n.
        For each i (1 ≤ i ≤ n), the value of a[i] = i * i - i + 1.
        Return the number of triples (a[i], a[j], a[k]) of a where i < j < k,
    and a[i] + a[j] + a[k] is a multiple of 3.

    Example :
        Input: n = 5
        Output: 1
        Explanation:
        a = [1, 3, 7, 13, 21]
        The only valid triple is (1, 7, 13).
    """

def get_max_triples(n):
    """
    Construct an array a of length n where a[i] = i*i - i + 1 (1-indexed).
    Count the number of triples (i,j,k) with i<j<k such that a[i]+a[j]+a[k] is divisible by 3.
    Example :
        Input: n = 5
        Output: 1
        Explanation:
        a = [1, 3, 7, 13, 21]
        The only valid triple is (1, 7, 13).
    """

Answer:
    A = [i*i - i + 1 for i in range(1,n+1)]
    ans = []
    for i in range(n):
        for j in range(i+1,n):
            for k in range(j+1,n):
                if (A[i]+A[j]+A[k])%3 == 0:
                    ans += [(A[i],A[j],A[k])]
    return len(ans)

def check(candidate):

    assert candidate(5) == 1
    assert candidate(6) == 4
    assert candidate(10) == 36
    assert candidate(100) == 53361


def bf(planet1, planet2):
    '''
    There are eight planets in our solar system: the closerst to the Sun
    is Mercury, the next one is Venus, then Earth, Mars, Jupiter, Saturn,
    Uranus, Neptune.
    Write a function that takes two planet names as strings planet1 and planet2.
    The function should return a tuple containing all planets whose orbits are
    located between the orbit of planet1 and the orbit of planet2, sorted by
    the proximity to the sun.
    The function should return an empty tuple if planet1 or planet2
    are not correct planet names.
    Examples
    bf("Jupiter", "Neptune") ==> ("Saturn", "Uranus")
    bf("Earth", "Mercury") ==> ("Venus")
    bf("Mercury", "Uranus") ==> ("Venus", "Earth", "Mars", "Jupiter", "Saturn")
    '''

def bf(planet1, planet2):
    '''
    Given two planet names (among Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune),
    return a tuple of all planets whose orbits lie strictly between the two given planets,
    ordered by their distance from the Sun. If either name is invalid, return an empty tuple.
    Examples
    bf("Jupiter", "Neptune") ==> ("Saturn", "Uranus")
    bf("Earth", "Mercury") ==> ("Venus")
    bf("Mercury", "Uranus") ==> ("Venus", "Earth", "Mars", "Jupiter", "Saturn")
    '''

Answer:
    planet_names = ("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune")
    if planet1 not in planet_names or planet2 not in planet_names or planet1 == planet2:
        return ()
    planet1_index = planet_names.index(planet1)
    planet2_index = planet_names.index(planet2)
    if planet1_index < planet2_index:
        return (planet_names[planet1_index + 1: planet2_index])
    else:
        return (planet_names[planet2_index + 1 : planet1_index])

def check(candidate):

    # Check some simple cases
    assert candidate("Jupiter", "Neptune") == ("Saturn", "Uranus"), "First test error: " + str(len(candidate("Jupiter", "Neptune")))
    assert candidate("Earth", "Mercury") == ("Venus",), "Second test error: " + str(candidate("Earth", "Mercury"))
    assert candidate("Mercury", "Uranus") == ("Venus", "Earth", "Mars", "Jupiter", "Saturn"), "Third test error: " + str(candidate("Mercury", "Uranus"))
    assert candidate("Neptune", "Venus") == ("Earth", "Mars", "Jupiter", "Saturn", "Uranus"), "Fourth test error: " + str(candidate("Neptune", "Venus"))

    # Check some edge cases that are easy to work out by hand.
    assert candidate("Earth", "Earth") == ()
    assert candidate("Mars", "Earth") == ()
    assert candidate("Jupiter", "Makemake") == ()


def sorted_list_sum(lst):
    """Write a function that accepts a list of strings as a parameter,
    deletes the strings that have odd lengths from it,
    and returns the resulted list with a sorted order,
    The list is always a list of strings and never an array of numbers,
    and it may contain duplicates.
    The order of the list should be ascending by length of each word, and you
    should return the list sorted by that rule.
    If two words have the same length, sort the list alphabetically.
    The function should return a list of strings in sorted order.
    You may assume that all words will have the same length.
    For example:
    assert list_sort(["aa", "a", "aaa"]) => ["aa"]
    assert list_sort(["ab", "a", "aaa", "cd"]) => ["ab", "cd"]
    """

def sorted_list_sum(lst):
    """Given a list of strings, remove all strings with odd lengths, then sort the
    remaining strings primarily by length (ascending) and secondarily alphabetically
    for ties. Return the sorted list.
    For example:
    assert list_sort(["aa", "a", "aaa"]) => ["aa"]
    assert list_sort(["ab", "a", "aaa", "cd"]) => ["ab", "cd"]
    """

Answer:
    lst.sort()
    new_lst = []
    for i in lst:
        if len(i)%2 == 0:
            new_lst.append(i)
    return sorted(new_lst, key=len)

def check(candidate):

    # Check some simple cases
    assert candidate(["aa", "a", "aaa"]) == ["aa"]
    assert candidate(["school", "AI", "asdf", "b"]) == ["AI", "asdf", "school"]
    assert candidate(["d", "b", "c", "a"]) == []
    assert candidate(["d", "dcba", "abcd", "a"]) == ["abcd", "dcba"]

    # Check some edge cases that are easy to work out by hand.
    assert candidate(["AI", "ai", "au"]) == ["AI", "ai", "au"]
    assert candidate(["a", "b", "b", "c", "c", "a"]) == []
    assert candidate(['aaaa', 'bbbb', 'dd', 'cc']) == ["cc", "dd", "aaaa", "bbbb"]


def x_or_y(n, x, y):
    """A simple program which should return the value of x if n is
    a prime number and should return the value of y otherwise.

    Examples:
    for x_or_y(7, 34, 12) == 34
    for x_or_y(15, 8, 5) == 5

    """

def x_or_y(n, x, y):
    """Implement a selector that yields x if the input integer n is prime; otherwise, yields y.

    Examples:
    for x_or_y(7, 34, 12) == 34
    for x_or_y(15, 8, 5) == 5
    """

Answer:
    if n == 1:
        return y
    for i in range(2, n):
        if n % i == 0:
            return y
            break
    else:
        return x

def check(candidate):

    # Check some simple cases
    assert candidate(7, 34, 12) == 34
    assert candidate(15, 8, 5) == 5
    assert candidate(3, 33, 5212) == 33
    assert candidate(1259, 3, 52) == 3
    assert candidate(7919, -1, 12) == -1
    assert candidate(3609, 1245, 583) == 583
    assert candidate(91, 56, 129) == 129
    assert candidate(6, 34, 1234) == 1234

    # Check some edge cases that are easy to work out by hand.
    assert candidate(1, 2, 0) == 0
    assert candidate(2, 2, 0) == 2


def double_the_difference(lst):
    '''
    Given a list of numbers, return the sum of squares of the numbers
    in the list that are odd. Ignore numbers that are negative or not integers.

    double_the_difference([1, 3, 2, 0]) == 1 + 9 + 0 + 0 = 10
    double_the_difference([-1, -2, 0]) == 0
    double_the_difference([9, -2]) == 81
    double_the_difference([0]) == 0

    If the input list is empty, return 0.
    '''

def double_the_difference(lst):
    '''
    Compute the sum of the squares of all odd-valued elements in the list, but exclude
    any non-integer or negative entries. An empty list yields 0.

    double_the_difference([1, 3, 2, 0]) == 1 + 9 + 0 + 0 = 10
    double_the_difference([-1, -2, 0]) == 0
    double_the_difference([9, -2]) == 81
    double_the_difference([0]) == 0

    If the input list is empty, return 0.
    '''

Answer: return sum([i**2 for i in lst if i > 0 and i%2!=0 and "." not in str(i)])

def check(candidate):

    # Check some simple cases
    assert candidate([]) == 0 , "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([5, 4]) == 25 , "This prints if this assert fails 2 (good for debugging!)"
    assert candidate([0.1, 0.2, 0.3]) == 0 , "This prints if this assert fails 3 (good for debugging!)"
    assert candidate([-10, -20, -30]) == 0 , "This prints if this assert fails 4 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert candidate([-1, -2, 8]) == 0, "This prints if this assert fails 5 (also good for debugging!)"
    assert candidate([0.2, 3, 5]) == 34, "This prints if this assert fails 6 (also good for debugging!)"
    lst = list(range(-99, 100, 2))
    odd_sum = sum([i**2 for i in lst if i%2!=0 and i > 0])
    assert candidate(lst) == odd_sum , "This prints if this assert fails 7 (good for debugging!)"


def compare(game,guess):
    """I think we all remember that feeling when the result of some long-awaited
    event is finally known. The feelings and thoughts you have at that moment are
    definitely worth noting down and comparing.
    Your task is to determine if a person correctly guessed the results of a number of matches.
    You are given two arrays of scores and guesses of equal length, where each index shows a match.
    Return an array of the same length denoting how far off each guess was. If they have guessed correctly,
    the value is 0, and if not, the value is the absolute difference between the guess and the score.

    example:

    compare([1,2,3,4,5,1],[1,2,3,4,2,-2]) -> [0,0,0,0,3,3]
    compare([0,5,0,0,0,4],[4,1,1,0,0,-2]) -> [4,4,1,0,0,6]
    """

def compare(game,guess):
    """Given two equal-length arrays representing actual scores and predicted scores
    for a series of matches, produce an array of the absolute differences between each
    corresponding pair. A perfect prediction yields 0 at that index.

    example:

    compare([1,2,3,4,5,1],[1,2,3,4,2,-2]) -> [0,0,0,0,3,3]
    compare([0,5,0,0,0,4],[4,1,1,0,0,-2]) -> [4,4,1,0,0,6]
    """

Answer: return [abs(x-y) for x,y in zip(game,guess)]

def check(candidate):

    # Check some simple cases
    assert candidate([1,2,3,4,5,1],[1,2,3,4,2,-2])==[0,0,0,0,3,3], "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([0,0,0,0,0,0],[0,0,0,0,0,0])==[0,0,0,0,0,0], "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1,2,3],[-1,-2,-3])==[2,4,6], "This prints if this assert fails 1 (good for debugging!)"
    assert candidate([1,2,3,5],[-1,2,3,4])==[2,0,0,1], "This prints if this assert fails 1 (good for debugging!)"

    # Check some edge cases that are easy to work out by hand.
    assert True, "This prints if this assert fails 2 (also good for debugging!)"


def Strongest_Extension(class_name, extensions):
    """You will be given the name of a class (a string) and a list of extensions.
    The extensions are to be used to load additional classes to the class. The
    strength of the extension is as follows: Let CAP be the number of the uppercase
    letters in the extension's name, and let SM be the number of lowercase letters
    in the extension's name, the strength is given by the fraction CAP - SM.
    You should find the strongest extension and return a string in this
    format: ClassName.StrongestExtensionName.
    If there are two or more extensions with the same strength, you should
    choose the one that comes first in the list.
    For example, if you are given "Slices" as the class and a list of the
    extensions: ['SErviNGSliCes', 'Cheese', 'StuFfed'] then you should
    return 'Slices.SErviNGSliCes' since 'SErviNGSliCes' is the strongest extension
    (its strength is -1).
    Example:
    for Strongest_Extension('my_class', ['AA', 'Be', 'CC']) == 'my_class.AA'
    """

def Strongest_Extension(class_name, extensions):
    """Given a class name string and a list of extension name strings, compute each
    extension's strength as (number of uppercase letters) - (number of lowercase letters).
    Select the extension with the highest strength; in case of a tie, pick the one
    that appears earliest in the list. Return the concatenation 'ClassName.StrongestExtension'.
    For example, if you are given "Slices" as the class and a list of the
    extensions: ['SErviNGSliCes', 'Cheese', 'StuFfed'] then you should
    return 'Slices.SErviNGSliCes' since 'SErviNGSliCes' is the strongest extension
    (its strength is -1).
    Example:
    for Strongest_Extension('my_class', ['AA', 'Be', 'CC']) == 'my_class.AA'
    """

Answer:
    strong = extensions[0]
    my_val = len([x for x in extensions[0] if x.isalpha() and x.isupper()]) - len([x for x in extensions[0] if x.isalpha() and x.islower()])
    for s in extensions:
        val = len([x for x in s if x.isalpha() and x.isupper()]) - len([x for x in s if x.isalpha() and x.islower()])
        if val > my_val:
            strong = s
            my_val = val

    ans = class_name + "." + strong
    return ans

def check(candidate):

    # Check some simple cases
    assert candidate('Watashi', ['tEN', 'niNE', 'eIGHt8OKe']) == 'Watashi.eIGHt8OKe'
    assert candidate('Boku123', ['nani', 'NazeDa', 'YEs.WeCaNe', '32145tggg']) == 'Boku123.YEs.WeCaNe'
    assert candidate('__YESIMHERE', ['t', 'eMptY', 'nothing', 'zeR00', 'NuLl__', '123NoooneB321']) == '__YESIMHERE.NuLl__'
    assert candidate('K', ['Ta', 'TAR', 't234An', 'cosSo']) == 'K.TAR'
    assert candidate('__HAHA', ['Tab', '123', '781345', '-_-']) == '__HAHA.123'
    assert candidate('YameRore', ['HhAas', 'okIWILL123', 'WorkOut', 'Fails', '-_-']) == 'YameRore.okIWILL123'
    assert candidate('finNNalLLly', ['Die', 'NowW', 'Wow', 'WoW']) == 'finNNalLLly.WoW'

    # Check some edge cases that are easy to work out by hand.
    assert candidate('_', ['Bb', '91245']) == '_.Bb'
    assert candidate('Sp', ['671235', 'Bb']) == 'Sp.671235'