id stringlengths 32 32 | language stringclasses 6
values | function_name stringclasses 58
values | function_code stringlengths 46 494 | edge_case_type stringlengths 3 26 | edge_case_description stringlengths 10 56 | test_framework stringclasses 5
values | unit_test stringlengths 49 293 | difficulty stringclasses 3
values |
|---|---|---|---|---|---|---|---|---|
8f5dff3040767b3d0e3be1c154c6ee82 | python | find_max | def find_max(nums: list[int]) -> int:
if not nums:
raise ValueError("List must not be empty")
return max(nums) | single_element | single-element list returns that element | pytest | def test_find_max_single():
assert find_max([42]) == 42 | easy |
1788eb26f588d778d8e55afa9ee47216 | java | clamp | public static double clamp(double value, double lo, double hi) {
return Math.max(lo, Math.min(hi, value));
} | within | value within range returned unchanged | junit4 | @Test
public void testClampWithin() {
assertEquals(5.0, clamp(5, 0, 10), 1e-9);
} | medium |
addf121b5d1613a2d31fe7307621156f | go | FindMax | func FindMax(nums []int) (int, error) {
if len(nums) == 0 {
return 0, errors.New("empty slice")
}
max := nums[0]
for _, v := range nums[1:] {
if v > max {
max = v
}
}
return max, nil
} | duplicates | duplicate max values return that max | testing | func TestFindMaxDuplicates(t *testing.T) {
v, _ := FindMax([]int{5, 5, 3})
if v != 5 {
t.Errorf("expected 5, got %v", v)
}
} | medium |
3c212b51bd9ea9c67889bdd414e6fe68 | javascript | uniqueBy | function uniqueBy(arr, key) {
const seen = new Set();
return arr.filter(item => {
const k = item[key];
if (seen.has(k)) return false;
seen.add(k);
return true;
});
} | no_duplicates | no duplicate keys passes all through | jest | test("uniqueBy no dups", () => {
const items = [{id:1},{id:2}];
expect(uniqueBy(items,"id").length).toBe(2);
}); | easy |
7c231578d42808899d8933a0ffe97e27 | rust | reverse_string | pub fn reverse_string(s: &str) -> String {
s.chars().rev().collect()
} | unicode | unicode chars reversed by char boundary | rust-test | #[test]
fn test_reverse_unicode() {
assert_eq!(reverse_string("héllo"), "olléh");
} | medium |
6a2de3841755f519993049225dd35276 | javascript | memoize | function memoize(fn) {
const cache = new Map();
return (...args) => {
const key = JSON.stringify(args);
if (cache.has(key)) return cache.get(key);
const result = fn(...args);
cache.set(key, result);
return result;
};
} | zero_arg | zero-argument function is cached after first call | jest | test("memoize no args", () => {
let calls = 0;
const fn = memoize(() => { calls++; return 42; });
expect(fn()).toBe(42);
expect(fn()).toBe(42);
expect(calls).toBe(1);
}); | medium |
4cbcb7a2bea1832d809934ef03a6ca55 | typescript | parseJSON | export function parseJSON<T>(s: string): T | null {
try {
return JSON.parse(s) as T;
} catch {
return null;
}
} | null_literal | 'null' string parses to null value | jest | test('parseJSON null literal', () => {
expect(parseJSON('null')).toBeNull();
}); | medium |
8612040f0ee4f49f60b57ed3b7f48922 | typescript | chunk | export function chunk<T>(arr: T[], size: number): T[][] {
if (size <= 0) throw new Error('size must be positive');
const result: T[][] = [];
for (let i = 0; i < arr.length; i += size) result.push(arr.slice(i, i + size));
return result;
} | size_zero | size 0 throws | jest | test('chunk zero size', () => {
expect(() => chunk([1,2,3], 0)).toThrow();
}); | medium |
0fb557da8453317d8d032f507c7e1c2a | typescript | chunk | export function chunk<T>(arr: T[], size: number): T[][] {
if (size <= 0) throw new Error('size must be positive');
const result: T[][] = [];
for (let i = 0; i < arr.length; i += size) result.push(arr.slice(i, i + size));
return result;
} | remainder | uneven length last chunk is smaller | jest | test('chunk remainder', () => {
expect(chunk([1,2,3,4,5],2)).toEqual([[1,2],[3,4],[5]]);
}); | medium |
180ccdd8db9c2ebe7bf7889adc9c3257 | python | gcd | def gcd(a: int, b: int) -> int:
while b:
a, b = b, a % b
return a | coprime | gcd of coprime numbers is 1 | pytest | def test_gcd_coprime():
assert gcd(13, 7) == 1 | medium |
85c8bda3653f84986142ed4b13db50e4 | python | celsius_to_fahrenheit | def celsius_to_fahrenheit(c: float) -> float:
return c * 9 / 5 + 32 | negative_celsius | negative Celsius converts to correct Fahrenheit | pytest | def test_celsius_negative():
assert celsius_to_fahrenheit(-40) == -40.0 | medium |
aea7c5e5132313af8e26894fea3d1588 | python | chunk_list | def chunk_list(lst: list, size: int) -> list[list]:
if size <= 0:
raise ValueError("size must be positive")
return [lst[i:i + size] for i in range(0, len(lst), size)] | exact_multiple | list length is exact multiple of chunk size | pytest | def test_chunk_exact():
assert chunk_list([1, 2, 3, 4], 2) == [[1, 2], [3, 4]] | easy |
3d71fbca6d366aa728075274984f1ce4 | python | fizzbuzz | def fizzbuzz(n: int) -> str:
if n % 15 == 0:
return "FizzBuzz"
if n % 3 == 0:
return "Fizz"
if n % 5 == 0:
return "Buzz"
return str(n) | not_divisible | number not divisible by 3 or 5 returns string of n | pytest | def test_fizzbuzz_plain():
assert fizzbuzz(7) == "7" | medium |
a32ed98cf96d9012c648921a362084d9 | python | factorial | def factorial(n: int) -> int:
if n < 0:
raise ValueError("n must be non-negative")
if n == 0:
return 1
return n * factorial(n - 1) | one_input | factorial of 1 is 1 | pytest | def test_factorial_one():
assert factorial(1) == 1 | easy |
ffb235335b0ef809c4cec992ef39596d | java | factorial | public static long factorial(int n) {
if (n < 0) throw new IllegalArgumentException("n must be non-negative");
long result = 1;
for (int i = 2; i <= n; i++) result *= i;
return result;
} | zero | factorial(0) is 1 | junit4 | @Test
public void testFactorialZero() {
assertEquals(1L, factorial(0));
} | easy |
457bd0bd1bb017bb43babf394df00a5c | python | cumulative_sum | def cumulative_sum(nums: list[int]) -> list[int]:
"""Return running cumulative sum of nums."""
result, total = [], 0
for n in nums:
total += n
result.append(total)
return result | empty_list | empty list returns empty list | pytest | def test_cumsum_empty():
assert cumulative_sum([]) == [] | easy |
aabab1f1c05a1017d430f38f2f5f78e3 | java | wordCount | public static Map<String, Integer> wordCount(String text) {
Map<String, Integer> counts = new HashMap<>();
if (text == null || text.isBlank()) return counts;
for (String word : text.toLowerCase().split("\\s+")) {
counts.merge(word, 1, Integer::sum);
}
return counts;
} | null_input | null input returns empty map | junit4 | @Test
public void testWordCountNull() {
assertTrue(wordCount(null).isEmpty());
} | medium |
c7470fa12d5ba01e87a7f9c8c40bd95c | java | findMax | public static int findMax(int[] arr) {
if (arr.length == 0) throw new IllegalArgumentException("Array is empty");
int max = arr[0];
for (int v : arr) if (v > max) max = v;
return max;
} | duplicates | max value appears multiple times | junit4 | @Test
public void testFindMaxDuplicates() {
assertEquals(5, findMax(new int[]{5, 5, 3}));
} | medium |
8f08b93f7068fd80a6c96537f9da42aa | java | reverseString | public static String reverseString(String s) {
return new StringBuilder(s).reverse().toString();
} | palindrome | palindrome returns itself | junit4 | @Test
public void testReversePalindrome() {
assertEquals("racecar", reverseString("racecar"));
} | easy |
6ed22e9d050c298707a04e77acccf275 | typescript | pick | export function pick<T extends object, K extends keyof T>(obj: T, keys: K[]): Pick<T, K> {
const result = {} as Pick<T, K>;
for (const k of keys) {
if (k in obj) result[k] = obj[k];
}
return result;
} | all_keys | picking all keys returns equivalent object | jest | test('pick all keys', () => {
expect(pick({a:1,b:2}, ['a','b'])).toEqual({a:1,b:2});
}); | easy |
1557f66d45ec09226cc6cc9593be7a2b | rust | divide | pub fn divide(a: f64, b: f64) -> Result<f64, String> {
if b == 0.0 {
return Err("Division by zero".to_string());
}
Ok(a / b)
} | both_negative | both negative yields positive | rust-test | #[test]
fn test_divide_both_neg() {
assert_eq!(divide(-6.0, -3.0).unwrap(), 2.0);
} | medium |
c798c3654d6c54b0d71a4cafefe1a856 | typescript | deepEqual | export function deepEqual(a: unknown, b: unknown): boolean {
return JSON.stringify(a) === JSON.stringify(b);
} | array_order | array order matters for equality | jest | test('deepEqual array order', () => {
expect(deepEqual([1,2], [2,1])).toBe(false);
}); | medium |
13ba608609022f7d7a6cf3d44b170c28 | rust | clamp | pub fn clamp(value: f64, lo: f64, hi: f64) -> f64 {
if value < lo { lo } else if value > hi { hi } else { value }
} | within | value within range unchanged | rust-test | #[test]
fn test_clamp_within() {
assert_eq!(clamp(5.0, 0.0, 10.0), 5.0);
} | medium |
cae23a2c6b4b1d23604ef44e5917d13e | javascript | divide | function divide(a, b) {
if (b === 0) throw new Error('Division by zero');
return a / b;
} | negative_inputs | negative numerator and positive divisor | jest | test("divide negative numerator", () => {
expect(divide(-10, 2)).toBe(-5);
}); | medium |
2e1b377a50fb8f018e87aad02e4883c4 | python | truncate | def truncate(s: str, max_len: int) -> str:
if len(s) <= max_len:
return s
return s[:max_len] + "..." | empty_string | empty string is returned unchanged | pytest | def test_truncate_empty():
assert truncate("", 5) == "" | easy |
d7fdafdec0c62c7e899b81deeac2db3b | java | divide | public static double divide(double a, double b) {
if (b == 0) throw new ArithmeticException("Division by zero");
return a / b;
} | both_negative | both negative operands yield positive | junit4 | @Test
public void testDivideBothNegative() {
assertEquals(2.0, divide(-6, -3), 1e-9);
} | medium |
45895352d09abbbb9c9cb89a6098023b | rust | divide | pub fn divide(a: f64, b: f64) -> Result<f64, String> {
if b == 0.0 {
return Err("Division by zero".to_string());
}
Ok(a / b)
} | zero_numerator | a=0 returns Ok(0) | rust-test | #[test]
fn test_divide_zero_num() {
assert_eq!(divide(0.0, 5.0).unwrap(), 0.0);
} | medium |
ea37442ebc50663de3c50c29671be0cc | python | is_palindrome | def is_palindrome(s: str) -> bool:
s = s.lower().replace(" ", "")
return s == s[::-1] | numeric_palindrome | numeric palindrome string is correctly identified | pytest | def test_is_palindrome_numeric():
assert is_palindrome("12321") is True | medium |
3f854021ffd8b18e508a4c93a8ea014b | go | FindMax | func FindMax(nums []int) (int, error) {
if len(nums) == 0 {
return 0, errors.New("empty slice")
}
max := nums[0]
for _, v := range nums[1:] {
if v > max {
max = v
}
}
return max, nil
} | empty_slice | empty slice returns error | testing | func TestFindMaxEmpty(t *testing.T) {
_, err := FindMax([]int{})
if err == nil {
t.Error("expected error for empty slice")
}
} | easy |
92065080d78afa9978d9888abe5eaa48 | typescript | groupBy | export function groupBy<T>(arr: T[], key: keyof T): Record<string, T[]> {
return arr.reduce((acc, item) => {
const k = String(item[key]);
if (!acc[k]) acc[k] = [];
acc[k].push(item);
return acc;
}, {} as Record<string, T[]>);
} | preserves_order | within each group order is preserved | jest | test('groupBy order', () => {
const items = [{k:'a',i:1},{k:'b',i:2},{k:'a',i:3}];
expect(groupBy(items,'k').a.map(x=>x.i)).toEqual([1,3]);
}); | medium |
4f3d1c32d94185a8bcc0ccdb521270cb | python | is_palindrome | def is_palindrome(s: str) -> bool:
s = s.lower().replace(" ", "")
return s == s[::-1] | case_insensitive | palindrome check is case-insensitive | pytest | def test_is_palindrome_case():
assert is_palindrome("Racecar") is True | medium |
a5a73e0d676dc91cd23561b3ec5fb7c9 | javascript | memoize | function memoize(fn) {
const cache = new Map();
return (...args) => {
const key = JSON.stringify(args);
if (cache.has(key)) return cache.get(key);
const result = fn(...args);
cache.set(key, result);
return result;
};
} | caches_result | memoized function returns cached result on second call | jest | test("memoize caches", () => {
let calls = 0;
const fn = memoize((x) => { calls++; return x * 2; });
fn(5);
fn(5);
expect(calls).toBe(1);
}); | medium |
52adbc9993afacd03336a571e102e5a5 | python | Stack | class Stack:
def __init__(self):
self._data = []
def push(self, item):
self._data.append(item)
def pop(self):
if not self._data:
raise IndexError("pop from empty stack")
return self._data.pop()
def peek(self):
if not self._data:
raise In... | push_duplicate_values | duplicate values are stored and returned in order | pytest | def test_stack_duplicates():
s = Stack()
s.push(7)
s.push(7)
assert s.pop() == 7
assert s.pop() == 7
assert s.is_empty() | medium |
8933f14b14463cd2a7fb394f56f7af71 | python | find_max | def find_max(nums: list[int]) -> int:
if not nums:
raise ValueError("List must not be empty")
return max(nums) | already_sorted | sorted list returns last element | pytest | def test_find_max_sorted():
assert find_max([1, 2, 3, 4, 5]) == 5 | medium |
8bd86f08f9fa5114c31cf1eef8bc27ae | python | Stack | class Stack:
def __init__(self):
self._data = []
def push(self, item):
self._data.append(item)
def pop(self):
if not self._data:
raise IndexError("pop from empty stack")
return self._data.pop()
def peek(self):
if not self._data:
raise In... | peek_empty | peeking empty stack raises IndexError | pytest | import pytest
def test_stack_peek_empty():
s = Stack()
with pytest.raises(IndexError):
s.peek() | medium |
7fdb430746cc2e3f688f219fd87e71db | javascript | clamp | function clamp(value, lo, hi) {
return Math.max(lo, Math.min(hi, value));
} | above_hi | value above hi returns hi | jest | test("clamp above hi", () => {
expect(clamp(15, 0, 10)).toBe(10);
}); | easy |
bcaed74b65864ccdae525bda7e7aacb2 | python | levenshtein | def levenshtein(s: str, t: str) -> int:
"""Compute Levenshtein (edit) distance between s and t."""
m, n = len(s), len(t)
dp = list(range(n + 1))
for i in range(1, m + 1):
prev = dp[0]
dp[0] = i
for j in range(1, n + 1):
tmp = dp[j]
if s[i-1] == t[j-1]:
... | completely_different | entirely different strings of equal length | pytest | def test_lev_different():
assert levenshtein("abc", "xyz") == 3 | medium |
472da75d55caa8c6c550bdb47556a461 | python | truncate | def truncate(s: str, max_len: int) -> str:
if len(s) <= max_len:
return s
return s[:max_len] + "..." | max_len_zero | max_len of 0 returns only ellipsis | pytest | def test_truncate_zero_max():
assert truncate("hello", 0) == "..." | medium |
116028ac4edfc0529916ac5fe8f57876 | javascript | countOccurrences | function countOccurrences(arr, val) {
return arr.filter(x => x === val).length;
} | empty_array | empty array returns 0 | jest | test("countOccurrences empty", () => {
expect(countOccurrences([], 5)).toBe(0);
}); | easy |
58685c535f2198b6b0339ba74e8fdcfb | javascript | debounce | function debounce(fn, delay) {
let timer;
return (...args) => {
clearTimeout(timer);
timer = setTimeout(() => fn(...args), delay);
};
} | fires_after_delay | debounced function fires once after delay | jest | test("debounce fires after delay", async () => {
jest.useFakeTimers();
const fn = jest.fn();
const debounced = debounce(fn, 100);
debounced();
debounced();
jest.runAllTimers();
expect(fn).toHaveBeenCalledTimes(1);
jest.useRealTimers();
}); | hard |
04ca7dcaa2d4532e1369973f9a222455 | typescript | flattenDeep | export function flattenDeep(arr: unknown[]): unknown[] {
const result: unknown[] = [];
const stack = [...arr];
while (stack.length) {
const item = stack.pop();
if (Array.isArray(item)) {
stack.push(...item);
} else {
result.unshift(item);
}
}
return result;
} | already_flat | already flat array returned unchanged | jest | test('flattenDeep flat', () => {
expect(flattenDeep([1,2,3])).toEqual([1,2,3]);
}); | easy |
064cc6e5a5371de7ec1417a2dd8f83be | python | merge_sorted | def merge_sorted(a: list[int], b: list[int]) -> list[int]:
"""Merge two sorted lists into one sorted list."""
result, i, j = [], 0, 0
while i < len(a) and j < len(b):
if a[i] <= b[j]:
result.append(a[i]); i += 1
else:
result.append(b[j]); j += 1
result.extend(a[i:... | unequal_lengths | one list much longer than the other | pytest | def test_merge_unequal():
assert merge_sorted([1, 2, 3, 4, 5], [3]) == [1, 2, 3, 3, 4, 5] | medium |
82aff88f7640f56a1e2e29f9101eb653 | java | divide | public static double divide(double a, double b) {
if (b == 0) throw new ArithmeticException("Division by zero");
return a / b;
} | negative_numerator | negative numerator returns correct result | junit4 | @Test
public void testDivideNegative() {
assertEquals(-5.0, divide(-10, 2), 1e-9);
} | medium |
4f452843be4f55e4e90a472eb4559f81 | python | Stack | class Stack:
def __init__(self):
self._data = []
def push(self, item):
self._data.append(item)
def pop(self):
if not self._data:
raise IndexError("pop from empty stack")
return self._data.pop()
def peek(self):
if not self._data:
raise In... | lifo_order | stack returns items in LIFO order | pytest | def test_stack_lifo():
s = Stack()
for v in [1, 2, 3]:
s.push(v)
assert s.pop() == 3
assert s.pop() == 2
assert s.pop() == 1 | easy |
7e27c43a012f026455db47b06855482b | javascript | debounce | function debounce(fn, delay) {
let timer;
return (...args) => {
clearTimeout(timer);
timer = setTimeout(() => fn(...args), delay);
};
} | resets_timer | rapid calls reset the timer and fire only once | jest | test("debounce resets timer", async () => {
jest.useFakeTimers();
const fn = jest.fn();
const debounced = debounce(fn, 200);
debounced();
jest.advanceTimersByTime(100);
debounced();
jest.advanceTimersByTime(200);
expect(fn).toHaveBeenCalledTimes(1);
jest.useRealTimers();
}); | hard |
f9ad51afefc4c39ca724895c0edfaf9b | go | Fibonacci | func Fibonacci(n int) (int, error) {
if n < 0 {
return 0, errors.New("n must be non-negative")
}
if n <= 1 {
return n, nil
}
a, b := 0, 1
for i := 2; i <= n; i++ {
a, b = b, a+b
}
return b, nil
} | two | Fibonacci(2) is 1 | testing | func TestFibTwo(t *testing.T) {
v, _ := Fibonacci(2)
if v != 1 {
t.Errorf("expected 1, got %d", v)
}
} | easy |
beee9e831285dc2e1b412c6bca93d200 | rust | find_max | pub fn find_max(nums: &[i64]) -> Option<i64> {
nums.iter().copied().reduce(i64::max)
} | empty_slice | empty slice returns None | rust-test | #[test]
fn test_find_max_empty() {
assert_eq!(find_max(&[]), None);
} | easy |
22b35ff787ab64456232ad8ae5dc4b95 | python | factorial | def factorial(n: int) -> int:
if n < 0:
raise ValueError("n must be non-negative")
if n == 0:
return 1
return n * factorial(n - 1) | two_input | factorial of 2 is 2 | pytest | def test_factorial_two():
assert factorial(2) == 2 | medium |
0c68ef8c2ed2328856e2c8e239dc61c8 | javascript | pipe | function pipe(...fns) {
return (x) => fns.reduce((v, f) => f(v), x);
} | order_matters | order of functions in pipe matters | jest | test("pipe order matters", () => {
const ab = pipe(x => x + 1, x => x * 2);
const ba = pipe(x => x * 2, x => x + 1);
expect(ab(3)).not.toBe(ba(3));
}); | hard |
84be0570bdd07e412bcda11ebce6596a | python | string_to_int | def string_to_int(s: str) -> int | None:
"""Parse s as integer, returning None on failure."""
try:
return int(s.strip())
except (ValueError, AttributeError):
return None | mixed_alpha_num | mixed alphanumeric string returns None | pytest | def test_str2int_mixed():
assert string_to_int('12abc') is None | medium |
f0f4800a0f7c9b5bee70041c8825a4e6 | javascript | reverseString | function reverseString(s) {
return s.split('').reverse().join('');
} | empty_string | reversing empty string returns empty string | jest | test("reverseString empty", () => {
expect(reverseString("")).toBe("");
}); | easy |
c9fd8ea6c914d41a90e84f393b7b89ab | javascript | chunk | function chunk(arr, size) {
if (size <= 0) throw new Error('size must be positive');
const result = [];
for (let i = 0; i < arr.length; i += size) {
result.push(arr.slice(i, i + size));
}
return result;
} | size_zero | chunk size of 0 throws | jest | test("chunk size zero throws", () => {
expect(() => chunk([1, 2], 0)).toThrow();
}); | medium |
dbfd5048f576d86924bad7da80b05051 | javascript | isPalindrome | function isPalindrome(s) {
const clean = s.toLowerCase().replace(/\s/g, '');
return clean === clean.split('').reverse().join('');
} | case_insensitive | case-insensitive check | jest | test("isPalindrome case insensitive", () => {
expect(isPalindrome("Racecar")).toBe(true);
}); | medium |
5be4052ac3cb712a6d4ea8225900dbc0 | python | find_max | def find_max(nums: list[int]) -> int:
if not nums:
raise ValueError("List must not be empty")
return max(nums) | duplicates | list with duplicate max values returns that max | pytest | def test_find_max_duplicates():
assert find_max([5, 5, 3, 5]) == 5 | medium |
74100c03270700dba3ec693e050f6b6d | java | reverseString | public static String reverseString(String s) {
return new StringBuilder(s).reverse().toString();
} | normal_word | normal word reversed correctly | junit4 | @Test
public void testReverseWord() {
assertEquals("olleh", reverseString("hello"));
} | medium |
62f0305c30c4c5e972e4a69702a02254 | typescript | omit | export function omit<T extends object, K extends keyof T>(obj: T, keys: K[]): Omit<T, K> {
const result = { ...obj };
for (const k of keys) delete result[k];
return result as Omit<T, K>;
} | nonexistent_key | omitting key not in object returns unchanged copy | jest | test('omit nonexistent', () => {
const result = omit({a:1} as any, ['z' as any]);
expect(result).toEqual({a:1});
}); | medium |
057bc92ea08d2f9d23ff25d42c704d72 | python | moving_average | def moving_average(data: list[float], window: int) -> list[float]:
if window <= 0:
raise ValueError("window must be positive")
return [sum(data[i:i+window]) / window for i in range(len(data) - window + 1)] | window_larger_than_data | window larger than data length returns empty list | pytest | def test_moving_avg_window_too_large():
assert moving_average([1.0, 2.0], 5) == [] | medium |
a50357228f693b6255d731d5bce70697 | python | string_to_int | def string_to_int(s: str) -> int | None:
"""Parse s as integer, returning None on failure."""
try:
return int(s.strip())
except (ValueError, AttributeError):
return None | none_input | None input returns None without raising | pytest | def test_str2int_none():
assert string_to_int(None) is None | medium |
98bf02cea9538d5f25aa06b57228b630 | java | clamp | public static double clamp(double value, double lo, double hi) {
return Math.max(lo, Math.min(hi, value));
} | above | value above hi returns hi | junit4 | @Test
public void testClampAbove() {
assertEquals(10.0, clamp(15, 0, 10), 1e-9);
} | medium |
6fd199fa4bcb05bd37ccc212f5761be6 | python | divide | def divide(a: float, b: float) -> float:
"""Return a divided by b."""
return a / b | float_precision | floating point inputs return correct quotient | pytest | def test_divide_float_precision():
result = divide(1.0, 3.0)
assert abs(result - 0.3333333333333333) < 1e-10 | medium |
59eeff85e6a15ffc8a3428275cad86f3 | java | factorial | public static long factorial(int n) {
if (n < 0) throw new IllegalArgumentException("n must be non-negative");
long result = 1;
for (int i = 2; i <= n; i++) result *= i;
return result;
} | ten | factorial(10) is 3628800 | junit4 | @Test
public void testFactorialTen() {
assertEquals(3628800L, factorial(10));
} | medium |
8e8165aa8e985d07ec0383963f13b94f | typescript | deepEqual | export function deepEqual(a: unknown, b: unknown): boolean {
return JSON.stringify(a) === JSON.stringify(b);
} | null_vs_undefined | null and undefined are not deeply equal | jest | test('deepEqual null vs undefined', () => {
expect(deepEqual(null, undefined)).toBe(false);
}); | hard |
ce36cd4b56e146d8e9544670db8395ce | python | deep_get | def deep_get(d: dict, *keys, default=None):
for key in keys:
if not isinstance(d, dict):
return default
d = d.get(key, default)
return d | missing_key | missing key returns default | pytest | def test_deep_get_missing():
assert deep_get({"a": 1}, "b") is None | medium |
1df270ba04b215bd06a39fc68bb3aa2f | python | levenshtein | def levenshtein(s: str, t: str) -> int:
"""Compute Levenshtein (edit) distance between s and t."""
m, n = len(s), len(t)
dp = list(range(n + 1))
for i in range(1, m + 1):
prev = dp[0]
dp[0] = i
for j in range(1, n + 1):
tmp = dp[j]
if s[i-1] == t[j-1]:
... | single_substitution | one character substitution has distance 1 | pytest | def test_lev_sub():
assert levenshtein("cat", "bat") == 1 | medium |
7db93dfdf319adc840c65449e5c2d11b | python | count_vowels | def count_vowels(s: str) -> int:
return sum(1 for c in s.lower() if c in "aeiou") | numbers_punctuation | digits and punctuation are not counted as vowels | pytest | def test_count_vowels_digits():
assert count_vowels("h3ll0!") == 0 | medium |
c791a38e27f3c4b26d4d2d54bee262f7 | rust | clamp | pub fn clamp(value: f64, lo: f64, hi: f64) -> f64 {
if value < lo { lo } else if value > hi { hi } else { value }
} | at_lo | value at lo returns lo | rust-test | #[test]
fn test_clamp_at_lo() {
assert_eq!(clamp(0.0, 0.0, 10.0), 0.0);
} | easy |
829f30edd436f25373ace690a2f1fa43 | javascript | uniqueBy | function uniqueBy(arr, key) {
const seen = new Set();
return arr.filter(item => {
const k = item[key];
if (seen.has(k)) return false;
seen.add(k);
return true;
});
} | empty_array | empty array returns empty | jest | test("uniqueBy empty", () => {
expect(uniqueBy([], "id")).toEqual([]);
}); | easy |
2a511df340f0c2d8765640bec66fc5b1 | rust | fibonacci | pub fn fibonacci(n: u64) -> u64 {
if n <= 1 { return n; }
let (mut a, mut b) = (0u64, 1u64);
for _ in 2..=n {
let c = a + b;
a = b;
b = c;
}
b
} | one | fibonacci(1) is 1 | rust-test | #[test]
fn test_fib_one() {
assert_eq!(fibonacci(1), 1);
} | easy |
6bfefb85c752c9b08756725952d03e9f | python | Stack | class Stack:
def __init__(self):
self._data = []
def push(self, item):
self._data.append(item)
def pop(self):
if not self._data:
raise IndexError("pop from empty stack")
return self._data.pop()
def peek(self):
if not self._data:
raise In... | is_empty_after_push | stack is not empty after push | pytest | def test_stack_not_empty_after_push():
s = Stack()
s.push(1)
assert s.is_empty() is False | easy |
f59e9a180e14d8ef9988da82b8a1039e | python | fizzbuzz | def fizzbuzz(n: int) -> str:
if n % 15 == 0:
return "FizzBuzz"
if n % 3 == 0:
return "Fizz"
if n % 5 == 0:
return "Buzz"
return str(n) | divisible_by_5 | multiple of 5 returns 'Buzz' | pytest | def test_fizzbuzz_buzz():
assert fizzbuzz(10) == "Buzz" | medium |
521b204d3ae8b9eabda42732616c4aef | python | chunk_list | def chunk_list(lst: list, size: int) -> list[list]:
if size <= 0:
raise ValueError("size must be positive")
return [lst[i:i + size] for i in range(0, len(lst), size)] | size_zero | chunk size of 0 raises ValueError | pytest | import pytest
def test_chunk_size_zero():
with pytest.raises(ValueError):
chunk_list([1, 2, 3], 0) | medium |
ee86829ff5e534cab3b4511ce015ac69 | rust | is_prime | pub fn is_prime(n: u64) -> bool {
if n < 2 { return false; }
if n == 2 { return true; }
if n % 2 == 0 { return false; }
let mut i = 3u64;
while i * i <= n {
if n % i == 0 { return false; }
i += 2;
}
true
} | zero | 0 is not prime | rust-test | #[test]
fn test_prime_zero() {
assert!(!is_prime(0));
} | easy |
9fce1f2e67d05d4901660137cf748fd2 | python | moving_average | def moving_average(data: list[float], window: int) -> list[float]:
if window <= 0:
raise ValueError("window must be positive")
return [sum(data[i:i+window]) / window for i in range(len(data) - window + 1)] | window_negative | negative window raises ValueError | pytest | import pytest
def test_moving_avg_negative_window():
with pytest.raises(ValueError):
moving_average([1.0, 2.0], -1) | medium |
811d9ec584cdfef63495c82e17ec9635 | python | divide | def divide(a: float, b: float) -> float:
"""Return a divided by b."""
return a / b | zero_numerator | zero divided by any nonzero number is zero | pytest | def test_divide_zero_numerator():
assert divide(0, 5) == 0.0 | medium |
f33153eced572d8813d58a3403039cbf | rust | is_prime | pub fn is_prime(n: u64) -> bool {
if n < 2 { return false; }
if n == 2 { return true; }
if n % 2 == 0 { return false; }
let mut i = 3u64;
while i * i <= n {
if n % i == 0 { return false; }
i += 2;
}
true
} | two | 2 is prime | rust-test | #[test]
fn test_prime_two() {
assert!(is_prime(2));
} | medium |
19e7bcbc7b925db29583f111af8563e9 | typescript | parseJSON | export function parseJSON<T>(s: string): T | null {
try {
return JSON.parse(s) as T;
} catch {
return null;
}
} | valid_array | valid JSON array is parsed | jest | test('parseJSON valid array', () => {
expect(parseJSON<number[]>('[1,2,3]')).toEqual([1,2,3]);
}); | easy |
66572fc65047a6aa6a86641614e6c133 | java | findMax | public static int findMax(int[] arr) {
if (arr.length == 0) throw new IllegalArgumentException("Array is empty");
int max = arr[0];
for (int v : arr) if (v > max) max = v;
return max;
} | single_element | single element returns that element | junit4 | @Test
public void testFindMaxSingle() {
assertEquals(42, findMax(new int[]{42}));
} | easy |
f9a17f44956d3b9d9b859022ffcdda44 | javascript | pipe | function pipe(...fns) {
return (x) => fns.reduce((v, f) => f(v), x);
} | empty_pipeline | empty pipe returns identity | jest | test("pipe empty", () => {
const id = pipe();
expect(id(5)).toBe(5);
}); | medium |
84ee4d197ab08c809f998c53f212adb5 | javascript | chunk | function chunk(arr, size) {
if (size <= 0) throw new Error('size must be positive');
const result = [];
for (let i = 0; i < arr.length; i += size) {
result.push(arr.slice(i, i + size));
}
return result;
} | exact_multiple | exact multiple length splits evenly | jest | test("chunk exact multiple", () => {
expect(chunk([1, 2, 3, 4], 2)).toEqual([[1, 2], [3, 4]]);
}); | easy |
922c121d72d4ed5bfbccf336614bd632 | go | ReverseString | func ReverseString(s string) string {
runes := []rune(s)
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
runes[i], runes[j] = runes[j], runes[i]
}
return string(runes)
} | empty | empty string returns empty | testing | func TestReverseEmpty(t *testing.T) {
if got := ReverseString(""); got != "" {
t.Errorf("expected "", got %q", got)
}
} | easy |
54a97350c385cf42290e993332c30b71 | go | Clamp | func Clamp(value, lo, hi float64) float64 {
if value < lo {
return lo
}
if value > hi {
return hi
}
return value
} | below_lo | value below lo returns lo | testing | func TestClampBelow(t *testing.T) {
if got := Clamp(-5, 0, 10); got != 0 {
t.Errorf("expected 0, got %v", got)
}
} | easy |
8179129e8620dcc3835bb3bb33d73fec | python | is_prime | def is_prime(n: int) -> bool:
if n < 2:
return False
for i in range(2, int(n**0.5) + 1):
if n % i == 0:
return False
return True | negative | negative numbers are not prime | pytest | def test_is_prime_negative():
assert is_prime(-7) is False | medium |
7fd3f7142e6c05e0953d0207f1cade69 | javascript | deepClone | function deepClone(obj) {
return JSON.parse(JSON.stringify(obj));
} | primitive | cloning a primitive number returns same value | jest | test("deepClone primitive", () => {
expect(deepClone(42)).toBe(42);
}); | medium |
28d363213762920384c8f131479ac3e5 | python | clamp | def clamp(value: float, lo: float, hi: float) -> float:
return max(lo, min(hi, value)) | lo_equals_hi | when lo equals hi, any value returns that bound | pytest | def test_clamp_lo_eq_hi():
assert clamp(5, 3, 3) == 3 | medium |
4dc390e3270fed55734dca7c655817a4 | javascript | findMax | function findMax(arr) {
if (arr.length === 0) throw new Error('Array is empty');
return Math.max(...arr);
} | duplicates | array with duplicates of max returns max | jest | test("findMax duplicates", () => {
expect(findMax([3, 3, 1])).toBe(3);
}); | medium |
79a947226bdeb15336b72fb46bb2c33a | python | zip_with | def zip_with(fn, a: list, b: list) -> list:
"""Apply fn element-wise to paired elements of a and b."""
return [fn(x, y) for x, y in zip(a, b)] | single_element | single element lists return single element | pytest | def test_zip_with_single():
assert zip_with(max, [3], [5]) == [5] | easy |
cbf7c0df91d42e482b01da2bcd2495a7 | python | chunk_list | def chunk_list(lst: list, size: int) -> list[list]:
if size <= 0:
raise ValueError("size must be positive")
return [lst[i:i + size] for i in range(0, len(lst), size)] | size_larger_than_list | chunk size larger than list returns one chunk | pytest | def test_chunk_size_larger():
assert chunk_list([1, 2], 10) == [[1, 2]] | easy |
f8f2d58db9f87c6b00124ebae0cc93b6 | typescript | omit | export function omit<T extends object, K extends keyof T>(obj: T, keys: K[]): Omit<T, K> {
const result = { ...obj };
for (const k of keys) delete result[k];
return result as Omit<T, K>;
} | all_keys | omitting all keys returns empty object | jest | test('omit all keys', () => {
expect(omit({a:1,b:2}, ['a','b'])).toEqual({});
}); | medium |
b38b6524071ad36e6636bd243c72c34f | rust | fibonacci | pub fn fibonacci(n: u64) -> u64 {
if n <= 1 { return n; }
let (mut a, mut b) = (0u64, 1u64);
for _ in 2..=n {
let c = a + b;
a = b;
b = c;
}
b
} | zero | fibonacci(0) is 0 | rust-test | #[test]
fn test_fib_zero() {
assert_eq!(fibonacci(0), 0);
} | easy |
a9a67db15023c73d8f058f9d1514658b | javascript | findMax | function findMax(arr) {
if (arr.length === 0) throw new Error('Array is empty');
return Math.max(...arr);
} | single_element | single element array returns that element | jest | test("findMax single element", () => {
expect(findMax([42])).toBe(42);
}); | easy |
9111917b13e869bca8630febc206b5d2 | typescript | chunk | export function chunk<T>(arr: T[], size: number): T[][] {
if (size <= 0) throw new Error('size must be positive');
const result: T[][] = [];
for (let i = 0; i < arr.length; i += size) result.push(arr.slice(i, i + size));
return result;
} | empty_array | empty array returns empty | jest | test('chunk empty', () => {
expect(chunk([], 3)).toEqual([]);
}); | easy |
db11f4bb1246b5bb787f63000e6f9e1e | go | Unique | func Unique(nums []int) []int {
seen := make(map[int]bool)
result := []int{}
for _, v := range nums {
if !seen[v] {
seen[v] = true
result = append(result, v)
}
}
return result
} | empty_slice | empty slice returns empty | testing | func TestUniqueEmpty(t *testing.T) {
result := Unique([]int{})
if len(result) != 0 {
t.Errorf("expected empty, got %v", result)
}
} | easy |
6544b0f0c1d605611fc063531287426f | java | factorial | public static long factorial(int n) {
if (n < 0) throw new IllegalArgumentException("n must be non-negative");
long result = 1;
for (int i = 2; i <= n; i++) result *= i;
return result;
} | one | factorial(1) is 1 | junit4 | @Test
public void testFactorialOne() {
assertEquals(1L, factorial(1));
} | easy |
c6171c53b84253d1e03389c679181b46 | python | factorial | def factorial(n: int) -> int:
if n < 0:
raise ValueError("n must be non-negative")
if n == 0:
return 1
return n * factorial(n - 1) | negative_input | negative input raises ValueError | pytest | import pytest
def test_factorial_negative():
with pytest.raises(ValueError):
factorial(-1) | medium |
788dfb9811f1ccf99dcaaaa2a4ce6cfe | rust | find_max | pub fn find_max(nums: &[i64]) -> Option<i64> {
nums.iter().copied().reduce(i64::max)
} | all_negative | all negative returns least negative | rust-test | #[test]
fn test_find_max_neg() {
assert_eq!(find_max(&[-3, -1, -7]), Some(-1));
} | medium |
7c38372669cab1258c155379a317351d | python | divide | def divide(a: float, b: float) -> float:
"""Return a divided by b."""
return a / b | negative_numerator | negative numerator returns correct negative result | pytest | def test_divide_negative_numerator():
assert divide(-10, 2) == -5.0 | medium |
7d2db485c51743d3ad14425af0bebeaf | python | reverse_string | def reverse_string(s: str) -> str:
return s[::-1] | whitespace | whitespace characters are preserved in reverse | pytest | def test_reverse_whitespace():
assert reverse_string("a b") == "b a" | medium |
f9b9362622345f254d8045ceb46f7b24 | javascript | pipe | function pipe(...fns) {
return (x) => fns.reduce((v, f) => f(v), x);
} | single_fn | pipe with single function applies it | jest | test("pipe single fn", () => {
const double = pipe(x => x * 2);
expect(double(3)).toBe(6);
}); | easy |
ccc73a8e1758e796d4a388ae656eb38b | rust | count_vowels | pub fn count_vowels(s: &str) -> usize {
s.chars().filter(|c| "aeiouAEIOU".contains(*c)).count()
} | uppercase | uppercase vowels counted | rust-test | #[test]
fn test_vowels_upper() {
assert_eq!(count_vowels("AEIOU"), 5);
} | medium |
465643b4c162f98272969caa5fac2e06 | python | zip_with | def zip_with(fn, a: list, b: list) -> list:
"""Apply fn element-wise to paired elements of a and b."""
return [fn(x, y) for x, y in zip(a, b)] | string_fn | string concatenation function applied element-wise | pytest | def test_zip_with_strings():
result = zip_with(lambda x, y: x + y, ['a', 'b'], ['1', '2'])
assert result == ['a1', 'b2'] | medium |
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