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apps_data_1900
Given a binary tree, write a function to get the maximum width of the given tree. The width of a tree is the maximum width among all levels. The binary tree has the same structure as a full binary tree, but some nodes are null. The width of one level is defined as the length between the end-nodes (the leftmost and ri...
apps_data_1901
In a 2D grid of 0s and 1s, we change at most one 0 to a 1. After, what is the size of the largest island? (An island is a 4-directionally connected group of 1s). Example 1: Input: [[1, 0], [0, 1]] Output: 3 Explanation: Change one 0 to 1 and connect two 1s, then we get an island with area = 3. Example 2: Input: [[1, 1...
apps_data_1902
An integer has sequential digits if and only if each digit in the number is one more than the previous digit. Return a sorted list of all the integers in the range [low, high] inclusive that have sequential digits.   Example 1: Input: low = 100, high = 300 Output: [123,234] Example 2: Input: low = 1000, high = 13000 Ou...
apps_data_1903
You are given an array points representing integer coordinates of some points on a 2D-plane, where points[i] = [xi, yi]. The cost of connecting two points [xi, yi] and [xj, yj] is the manhattan distance between them: |xi - xj| + |yi - yj|, where |val| denotes the absolute value of val. Return the minimum cost to make a...
apps_data_1904
We have a list of points on the plane.  Find the K closest points to the origin (0, 0). (Here, the distance between two points on a plane is the Euclidean distance.) You may return the answer in any order.  The answer is guaranteed to be unique (except for the order that it is in.)   Example 1: Input: points = [[1,3],...
apps_data_1905
Given a set of distinct positive integers, find the largest subset such that every pair (Si, Sj) of elements in this subset satisfies: Si % Sj = 0 or Sj % Si = 0. If there are multiple solutions, return any subset is fine. Example 1: nums: [1,2,3] Result: [1,2] (of course, [1,3] will also be ok) Example 2: nu...
apps_data_1906
Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k), where h is the height of the person and k is the number of people in front of this person who have a height greater than or equal to h. Write an algorithm to reconstruct the queue. Note: The number of ...
apps_data_1907
Given two binary trees original and cloned and given a reference to a node target in the original tree. The cloned tree is a copy of the original tree. Return a reference to the same node in the cloned tree. Note that you are not allowed to change any of the two trees or the target node and the answer must be a referen...
apps_data_1908
Given a complete binary tree, count the number of nodes. Note: Definition of a complete binary tree from Wikipedia: In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the l...
apps_data_1909
Given a 2D grid of 0s and 1s, return the number of elements in the largest square subgrid that has all 1s on its border, or 0 if such a subgrid doesn't exist in the grid.   Example 1: Input: grid = [[1,1,1],[1,0,1],[1,1,1]] Output: 9 Example 2: Input: grid = [[1,1,0,0]] Output: 1   Constraints: 1 <= grid.length <= 1...
apps_data_1910
Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. k is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is. Example: Given this linked list...
apps_data_1911
Sort a linked list in O(n log n) time using constant space complexity. Example 1: Input: 4->2->1->3 Output: 1->2->3->4 Example 2: Input: -1->5->3->4->0 Output: -1->0->3->4->5 # Definition for singly-linked list. # class ListNode: # def __init__(self, x): # self.val = x # self.next = None...
apps_data_1912
Given many words, words[i] has weight i. Design a class WordFilter that supports one function, WordFilter.f(String prefix, String suffix). It will return the word with given prefix and suffix with maximum weight. If no word exists, return -1. Examples: Input: WordFilter(["apple"]) WordFilter.f("a", "e") // returns...
apps_data_1913
Given an array A of positive integers (not necessarily distinct), return the lexicographically largest permutation that is smaller than A, that can be made with one swap (A swap exchanges the positions of two numbers A[i] and A[j]).  If it cannot be done, then return the same array.   Example 1: Input: [3,2,1] Output: ...
apps_data_1914
A company is planning to interview 2n people. Given the array costs where costs[i] = [aCosti, bCosti], the cost of flying the ith person to city a is aCosti, and the cost of flying the ith person to city b is bCosti. Return the minimum cost to fly every person to a city such that exactly n people arrive in each city.  ...
apps_data_1915
You want to form a target string of lowercase letters. At the beginning, your sequence is target.length '?' marks.  You also have a stamp of lowercase letters. On each turn, you may place the stamp over the sequence, and replace every letter in the sequence with the corresponding letter from the stamp.  You can make up...
apps_data_1916
Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path must contain at least one node and does not need to go through the root. Example 1: Input: [1,2,3] ...
apps_data_1917
Given a chemical formula (given as a string), return the count of each atom. An atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name. 1 or more digits representing the count of that element may follow if the count is greater than 1. If the count is 1, n...
apps_data_1918
Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the itinerary must begin with JFK. Note: If there are multiple valid itineraries, you should return the itinerar...
apps_data_1919
There are a total of n courses you have to take, labeled from 0 to n-1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a list of prerequisite pairs, return the ordering of courses you should t...
apps_data_1920
Create a timebased key-value store class TimeMap, that supports two operations. 1. set(string key, string value, int timestamp) Stores the key and value, along with the given timestamp. 2. get(string key, int timestamp) Returns a value such that set(key, value, timestamp_prev) was called previously, with timestamp_p...
apps_data_1921
You have an infinite number of stacks arranged in a row and numbered (left to right) from 0, each of the stacks has the same maximum capacity. Implement the DinnerPlates class: DinnerPlates(int capacity) Initializes the object with the maximum capacity of the stacks. void push(int val) Pushes the given positive intege...
apps_data_1922
Given a binary tree, we install cameras on the nodes of the tree.  Each camera at a node can monitor its parent, itself, and its immediate children. Calculate the minimum number of cameras needed to monitor all nodes of the tree.   Example 1: Input: [0,0,null,0,0] Output: 1 Explanation: One camera is enough to monito...
apps_data_1923
You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smaller elements to the right of nums[i]. Example: Input: [5,2,6,1] Output: [2,1,1,0] Explanation: To the right of 5 there are 2 smaller elements (2 and 1). To the right ...
apps_data_1924
A transaction is possibly invalid if: the amount exceeds $1000, or; if it occurs within (and including) 60 minutes of another transaction with the same name in a different city. Each transaction string transactions[i] consists of comma separated values representing the name, time (in minutes), amount, and city of the...
apps_data_1925
Return the root node of a binary search tree that matches the given preorder traversal. (Recall that a binary search tree is a binary tree where for every node, any descendant of node.left has a value < node.val, and any descendant of node.right has a value > node.val.  Also recall that a preorder traversal displays th...
apps_data_1926
Given an integer num, find the closest two integers in absolute difference whose product equals num + 1 or num + 2. Return the two integers in any order.   Example 1: Input: num = 8 Output: [3,3] Explanation: For num + 1 = 9, the closest divisors are 3 & 3, for num + 2 = 10, the closest divisors are 2 & 5, hence 3 & 3 ...
apps_data_1927
We are given an array asteroids of integers representing asteroids in a row. For each asteroid, the absolute value represents its size, and the sign represents its direction (positive meaning right, negative meaning left). Each asteroid moves at the same speed. Find out the state of the asteroids after all collision...
apps_data_1928
Given a nested list of integers represented as a string, implement a parser to deserialize it. Each element is either an integer, or a list -- whose elements may also be integers or other lists. Note: You may assume that the string is well-formed: String is non-empty. String does not contain white spaces. String con...
apps_data_1929
Implement the StreamChecker class as follows: StreamChecker(words): Constructor, init the data structure with the given words. query(letter): returns true if and only if for some k >= 1, the last k characters queried (in order from oldest to newest, including this letter just queried) spell one of the words in the giv...
apps_data_1930
There is a sale in a supermarket, there will be a discount every n customer. There are some products in the supermarket where the id of the i-th product is products[i] and the price per unit of this product is prices[i]. The system will count the number of customers and when the n-th customer arrive he/she will have a ...
apps_data_1931
Given a binary tree root and a linked list with head as the first node.  Return True if all the elements in the linked list starting from the head correspond to some downward path connected in the binary tree otherwise return False. In this context downward path means a path that starts at some node and goes downwards....
apps_data_1932
Two players play a turn based game on a binary tree.  We are given the root of this binary tree, and the number of nodes n in the tree.  n is odd, and each node has a distinct value from 1 to n. Initially, the first player names a value x with 1 <= x <= n, and the second player names a value y with 1 <= y <= n and y !=...
apps_data_1933
Given two strings representing two complex numbers. You need to return a string representing their multiplication. Note i2 = -1 according to the definition. Example 1: Input: "1+1i", "1+1i" Output: "0+2i" Explanation: (1 + i) * (1 + i) = 1 + i2 + 2 * i = 2i, and you need convert it to the form of 0+2i. Example ...
apps_data_1934
Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its zigzag level order traversal as: [ ...
apps_data_1935
In a string composed of 'L', 'R', and 'X' characters, like "RXXLRXRXL", a move consists of either replacing one occurrence of "XL" with "LX", or replacing one occurrence of "RX" with "XR". Given the starting string start and the ending string end, return True if and only if there exists a sequence of moves to transform...
apps_data_1936
In an infinite binary tree where every node has two children, the nodes are labelled in row order. In the odd numbered rows (ie., the first, third, fifth,...), the labelling is left to right, while in the even numbered rows (second, fourth, sixth,...), the labelling is right to left. Given the label of a node in this ...
apps_data_1937
A kingdom consists of a king, his children, his grandchildren, and so on. Every once in a while, someone in the family dies or a child is born. The kingdom has a well-defined order of inheritance that consists of the king as the first member. Let's define the recursive function Successor(x, curOrder), which given a per...
apps_data_1938
We are given a list of (axis-aligned) rectangles.  Each rectangle[i] = [x1, y1, x2, y2] , where (x1, y1) are the coordinates of the bottom-left corner, and (x2, y2) are the coordinates of the top-right corner of the ith rectangle. Find the total area covered by all rectangles in the plane.  Since the answer may be too ...
apps_data_1939
Given a wordlist, we want to implement a spellchecker that converts a query word into a correct word. For a given query word, the spell checker handles two categories of spelling mistakes: Capitalization: If the query matches a word in the wordlist (case-insensitive), then the query word is returned with the same case...
apps_data_1940
We are given a linked list with head as the first node.  Let's number the nodes in the list: node_1, node_2, node_3, ... etc. Each node may have a next larger value: for node_i, next_larger(node_i) is the node_j.val such that j > i, node_j.val > node_i.val, and j is the smallest possible choice.  If such a j does not e...
apps_data_1941
With respect to a given puzzle string, a word is valid if both the following conditions are satisfied: word contains the first letter of puzzle. For each letter in word, that letter is in puzzle. For example, if the puzzle is "abcdefg", then valid words are "faced", "cabbage", and "baggage"; while invalid word...
apps_data_1942
Given the array favoriteCompanies where favoriteCompanies[i] is the list of favorites companies for the ith person (indexed from 0). Return the indices of people whose list of favorite companies is not a subset of any other list of favorites companies. You must return the indices in increasing order.   Example 1: Input...
apps_data_1943
Given two lists of closed intervals, each list of intervals is pairwise disjoint and in sorted order. Return the intersection of these two interval lists. (Formally, a closed interval [a, b] (with a <= b) denotes the set of real numbers x with a <= x <= b.  The intersection of two closed intervals is a set of real numb...
apps_data_1944
Solve a given equation and return the value of x in the form of string "x=#value". The equation contains only '+', '-' operation, the variable x and its coefficient. If there is no solution for the equation, return "No solution". If there are infinite solutions for the equation, return "Infinite solutions". If t...
apps_data_1945
Given a matrix consisting of 0s and 1s, we may choose any number of columns in the matrix and flip every cell in that column.  Flipping a cell changes the value of that cell from 0 to 1 or from 1 to 0. Return the maximum number of rows that have all values equal after some number of flips.   Example 1: Input: [[0,1]...
apps_data_1946
Design a simplified version of Twitter where users can post tweets, follow/unfollow another user and is able to see the 10 most recent tweets in the user's news feed. Your design should support the following methods: postTweet(userId, tweetId): Compose a new tweet. getNewsFeed(userId): Retrieve the 10 most recent tw...
apps_data_1947
We are given two arrays A and B of words.  Each word is a string of lowercase letters. Now, say that word b is a subset of word a if every letter in b occurs in a, including multiplicity.  For example, "wrr" is a subset of "warrior", but is not a subset of "world". Now say a word a from A is universal if for every b in...
apps_data_1948
You have a very large square wall and a circular dartboard placed on the wall. You have been challenged to throw darts into the board blindfolded. Darts thrown at the wall are represented as an array of points on a 2D plane.  Return the maximum number of points that are within or lie on any circular dartboard of radius...
apps_data_1949
In a gold mine grid of size m * n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty. Return the maximum amount of gold you can collect under the conditions: Every time you are located in a cell you will collect all the gold in that cell. From your position you can wa...
apps_data_1950
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Example 1: Input: 1->2->3->3->4->4->5 Output: 1->2->5 Example 2: Input: 1->1->1->2->3 Output: 2->3 # Definition for singly-linked list. # class ListNode: # def __init__(self, x):...
apps_data_1951
We are given the root node of a maximum tree: a tree where every node has a value greater than any other value in its subtree. Just as in the previous problem, the given tree was constructed from an list A (root = Construct(A)) recursively with the following Construct(A) routine: If A is empty, return null. Otherwise,...
apps_data_1952
Reverse a linked list from position m to n. Do it in one-pass. Note: 1 ≤ m ≤ n ≤ length of list. Example: Input: 1->2->3->4->5->NULL, m = 2, n = 4 Output: 1->4->3->2->5->NULL class Solution: def reverseBetween(self, head, m, n): """ :type head: ListNode :type m: int :type n...
apps_data_1953
Given a linked list, remove the n-th node from the end of list and return its head. Example: Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5. Note: Given n will always be valid. Follow up: Could you do this in one pass? # Definition ...
apps_data_1954
In a project, you have a list of required skills req_skills, and a list of people.  The i-th person people[i] contains a list of skills that person has. Consider a sufficient team: a set of people such that for every required skill in req_skills, there is at least one person in the team who has that skill.  We can repr...
apps_data_1955
You are given a string s, and an array of pairs of indices in the string pairs where pairs[i] = [a, b] indicates 2 indices(0-indexed) of the string. You can swap the characters at any pair of indices in the given pairs any number of times. Return the lexicographically smallest string that s can be changed to after usin...
apps_data_1956
Write a program to solve a Sudoku puzzle by filling the empty cells. A sudoku solution must satisfy all of the following rules: Each of the digits 1-9 must occur exactly once in each row. Each of the digits 1-9 must occur exactly once in each column. Each of the the digits 1-9 must occur exactly...
apps_data_1957
Given a m * n grid, where each cell is either 0 (empty) or 1 (obstacle). In one step, you can move up, down, left or right from and to an empty cell. Return the minimum number of steps to walk from the upper left corner (0, 0) to the lower right corner (m-1, n-1) given that you can eliminate at most k obstacles. If it ...
apps_data_1958
There are n people that are split into some unknown number of groups. Each person is labeled with a unique ID from 0 to n - 1. You are given an integer array groupSizes, where groupSizes[i] is the size of the group that person i is in. For example, if groupSizes[1] = 3, then person 1 must be in a group of size 3. Retur...
apps_data_1959
We stack glasses in a pyramid, where the first row has 1 glass, the second row has 2 glasses, and so on until the 100th row.  Each glass holds one cup (250ml) of champagne. Then, some champagne is poured in the first glass at the top.  When the top most glass is full, any excess liquid poured will fall equally to the ...
apps_data_1960
Given the array queries of positive integers between 1 and m, you have to process all queries[i] (from i=0 to i=queries.length-1) according to the following rules: In the beginning, you have the permutation P=[1,2,3,...,m]. For the current i, find the position of queries[i] in the permutation P (indexing from 0) and t...
apps_data_1961
You have a browser of one tab where you start on the homepage and you can visit another url, get back in the history number of steps or move forward in the history number of steps. Implement the BrowserHistory class: BrowserHistory(string homepage) Initializes the object with the homepage of the browser. void visit(st...
apps_data_1962
Find the minimum length word from a given dictionary words, which has all the letters from the string licensePlate. Such a word is said to complete the given string licensePlate Here, for letters we ignore case. For example, "P" on the licensePlate still matches "p" on the word. It is guaranteed an answer exists. ...
apps_data_1963
In LeetCode Store, there are some kinds of items to sell. Each item has a price. However, there are some special offers, and a special offer consists of one or more different kinds of items with a sale price. You are given the each item's price, a set of special offers, and the number we need to buy for each item...
apps_data_1964
Print a binary tree in an m*n 2D string array following these rules: The row number m should be equal to the height of the given binary tree. The column number n should always be an odd number. The root node's value (in string format) should be put in the exactly middle of the first row it can be put. The column and...
apps_data_1965
Alice and Bob have an undirected graph of n nodes and 3 types of edges: Type 1: Can be traversed by Alice only. Type 2: Can be traversed by Bob only. Type 3: Can by traversed by both Alice and Bob. Given an array edges where edges[i] = [typei, ui, vi] represents a bidirectional edge of type typei between nodes ui and...
apps_data_1966
Given a rows * columns matrix mat of ones and zeros, return how many submatrices have all ones.   Example 1: Input: mat = [[1,0,1],   [1,1,0],   [1,1,0]] Output: 13 Explanation: There are 6 rectangles of side 1x1. There are 2 rectangles of side 1x2. There are 3 rectangles of side 2x1. There is 1...
apps_data_1967
Given a string S of digits, such as S = "123456579", we can split it into a Fibonacci-like sequence [123, 456, 579]. Formally, a Fibonacci-like sequence is a list F of non-negative integers such that: 0 <= F[i] <= 2^31 - 1, (that is, each integer fits a 32-bit signed integer type); F.length >= 3; and F[i] + F[i+1] = F...
apps_data_1968
Given a list of folders, remove all sub-folders in those folders and return in any order the folders after removing. If a folder[i] is located within another folder[j], it is called a sub-folder of it. The format of a path is one or more concatenated strings of the form: / followed by one or more lowercase English lett...
apps_data_1969
Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum of all root-to-leaf numbers. Note: A leaf is a node with no children. Example: Input: [1,2,3] 1 / \ 2 3 O...
apps_data_1970
Given an integer n, find the closest integer (not including itself), which is a palindrome. The 'closest' is defined as absolute difference minimized between two integers. Example 1: Input: "123" Output: "121" Note: The input n is a positive integer represented by string, whose length will not exceed 18. If the...
apps_data_1971
Given a 2D binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area. Example: Input: 1 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0 1 0 Output: 4 class Solution: def maximalSquare(self, matrix): """ :type matrix: List[List[str]] :rtype: int ...
apps_data_1972
S and T are strings composed of lowercase letters. In S, no letter occurs more than once. S was sorted in some custom order previously. We want to permute the characters of T so that they match the order that S was sorted. More specifically, if x occurs before y in S, then x should occur before y in the returned strin...
apps_data_1973
We have two types of tiles: a 2x1 domino shape, and an "L" tromino shape. These shapes may be rotated. XX <- domino XX <- "L" tromino X Given N, how many ways are there to tile a 2 x N board? Return your answer modulo 10^9 + 7. (In a tiling, every square must be covered by a tile. Two tilings are different if a...
apps_data_1974
Given a binary tree, return the postorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [3,2,1] Follow up: Recursive solution is trivial, could you do it iteratively? # Definition for a binary tree node. # class TreeNode: # def __init__(self, x): # ...
apps_data_1975
Design a stack which supports the following operations. Implement the CustomStack class: CustomStack(int maxSize) Initializes the object with maxSize which is the maximum number of elements in the stack or do nothing if the stack reached the maxSize. void push(int x) Adds x to the top of the stack if the stack hasn't ...
apps_data_1976
Implement a magic directory with buildDict, and search methods. For the method buildDict, you'll be given a list of non-repetitive words to build a dictionary. For the method search, you'll be given a word, and judge whether if you modify exactly one character into another character in this word, the modified wor...
apps_data_1977
Given a 2D grid consists of 0s (land) and 1s (water).  An island is a maximal 4-directionally connected group of 0s and a closed island is an island totally (all left, top, right, bottom) surrounded by 1s. Return the number of closed islands.   Example 1: Input: grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1...
apps_data_1978
You have a list of words and a pattern, and you want to know which words in words matches the pattern. A word matches the pattern if there exists a permutation of letters p so that after replacing every letter x in the pattern with p(x), we get the desired word. (Recall that a permutation of letters is a bijection from...
apps_data_1979
Given an array arr of 4 digits, find the latest 24-hour time that can be made using each digit exactly once. 24-hour times are formatted as "HH:MM", where HH is between 00 and 23, and MM is between 00 and 59. The earliest 24-hour time is 00:00, and the latest is 23:59. Return the latest 24-hour time in "HH:MM" format. ...
apps_data_1980
Design a Skiplist without using any built-in libraries. A Skiplist is a data structure that takes O(log(n)) time to add, erase and search. Comparing with treap and red-black tree which has the same function and performance, the code length of Skiplist can be comparatively short and the idea behind Skiplists are just si...
apps_data_1981
We have an array of integers, nums, and an array of requests where requests[i] = [starti, endi]. The ith request asks for the sum of nums[starti] + nums[starti + 1] + ... + nums[endi - 1] + nums[endi]. Both starti and endi are 0-indexed. Return the maximum total sum of all requests among all permutations of nums. Since...
apps_data_1982
Given a set of N people (numbered 1, 2, ..., N), we would like to split everyone into two groups of any size. Each person may dislike some other people, and they should not go into the same group.  Formally, if dislikes[i] = [a, b], it means it is not allowed to put the people numbered a and b into the same group. Retu...
apps_data_1983
Implement the class ProductOfNumbers that supports two methods: 1. add(int num) Adds the number num to the back of the current list of numbers. 2. getProduct(int k) Returns the product of the last k numbers in the current list. You can assume that always the current list has at least k numbers. At any time, the pro...
apps_data_1984
Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. For example, given preorder = [3,9,20,15,7] inorder = [9,3,15,20,7] Return the following binary tree: 3 / \ 9 20 / \ 15 7 # Definition for a binary tree n...
apps_data_1985
Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted in ascending from left to right. Integers in each column are sorted in ascending from top to bottom. Example: Consider the following matrix: [ [1, ...
apps_data_1986
Given 2 integers n and start. Your task is return any permutation p of (0,1,2.....,2^n -1) such that : p[0] = start p[i] and p[i+1] differ by only one bit in their binary representation. p[0] and p[2^n -1] must also differ by only one bit in their binary representation.   Example 1: Input: n = 2, start = 3 Output: [3...
apps_data_1987
We are stacking blocks to form a pyramid. Each block has a color which is a one letter string, like `'Z'`. For every block of color `C` we place not in the bottom row, we are placing it on top of a left block of color `A` and right block of color `B`. We are allowed to place the block there only if `(A, B, C)` is an...
apps_data_1988
Consider a directed graph, with nodes labelled 0, 1, ..., n-1.  In this graph, each edge is either red or blue, and there could be self-edges or parallel edges. Each [i, j] in red_edges denotes a red directed edge from node i to node j.  Similarly, each [i, j] in blue_edges denotes a blue directed edge from node i to n...
apps_data_1989
Given a string s. An awesome substring is a non-empty substring of s such that we can make any number of swaps in order to make it palindrome. Return the length of the maximum length awesome substring of s.   Example 1: Input: s = "3242415" Output: 5 Explanation: "24241" is the longest awesome substring, we can form th...
apps_data_1990
You are given n pairs of numbers. In every pair, the first number is always smaller than the second number. Now, we define a pair (c, d) can follow another pair (a, b) if and only if b < c. Chain of pairs can be formed in this fashion. Given a set of pairs, find the length longest chain which can be formed. You ...
apps_data_1991
You are given an array of distinct positive integers locations where locations[i] represents the position of city i. You are also given integers start, finish and fuel representing the starting city, ending city, and the initial amount of fuel you have, respectively. At each step, if you are at city i, you can pick any...
apps_data_1992
Design an Iterator class, which has: A constructor that takes a string characters of sorted distinct lowercase English letters and a number combinationLength as arguments. A function next() that returns the next combination of length combinationLength in lexicographical order. A function hasNext() that returns True if...
apps_data_1993
Given a C++ program, remove comments from it. The program source is an array where source[i] is the i-th line of the source code. This represents the result of splitting the original source code string by the newline character \n. In C++, there are two types of comments, line comments, and block comments. The string...
apps_data_1994
We are given head, the head node of a linked list containing unique integer values. We are also given the list G, a subset of the values in the linked list. Return the number of connected components in G, where two values are connected if they appear consecutively in the linked list. Example 1: Input: head: 0->1->2->3...
apps_data_1995
You are driving a vehicle that has capacity empty seats initially available for passengers.  The vehicle only drives east (ie. it cannot turn around and drive west.) Given a list of trips, trip[i] = [num_passengers, start_location, end_location] contains information about the i-th trip: the number of passengers that mu...
apps_data_1996
In a directed graph, we start at some node and every turn, walk along a directed edge of the graph.  If we reach a node that is terminal (that is, it has no outgoing directed edges), we stop. Now, say our starting node is eventually safe if and only if we must eventually walk to a terminal node.  More specifically, the...
apps_data_1997
Given a list of intervals, remove all intervals that are covered by another interval in the list. Interval [a,b) is covered by interval [c,d) if and only if c <= a and b <= d. After doing so, return the number of remaining intervals.   Example 1: Input: intervals = [[1,4],[3,6],[2,8]] Output: 2 Explanation: Interval [3...
apps_data_1998
There are n cities connected by m flights. Each fight starts from city u and arrives at v with a price w. Now given all the cities and fights, together with starting city src and the destination dst, your task is to find the cheapest price from src to dst with up to k stops. If there is no such route, output -1. Exa...
apps_data_1999
Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences. After doing so, return the head of the final linked list.  You may return any such answer.   (Note that in the examples below, all sequences are serializations of ListNode objects.) Exam...