You are given a 2D array of integers envelopes where envelopes[i] = [wi, hi]

You are given the root of a binary tree with n nodes, where each node is uniquely assigned a value from 1 to n.

Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order.

Given a string, your task is to count how many palindromic substrings in this string.

We are given two arrays A and B of words. Each word is a string of lowercase letters.

Given an m x n matrix of non-negative integers representing the height of each unit cell in a continent,

Ad Hoc Testing

unstructed testing type, also called random testing

Given two arrays A and B of equal size, the advantage of A with respect to B is the number of indices i for which A[i] > B[i].

Given an integer array arr, and an integer target, return the number of tuples i, j, k such that i < j < k and arr[i] + arr[j] + arr[k] == target.

Given a wordlist, we want to implement a spellchecker that converts a query word into a correct word.