Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise.

Given the head of a singly linked list, reverse the list, and return the reversed list.

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:

You are given two binary trees root1 and root2.

Given a string s, find the length of the longest substring without repeating characters.

Given the head of a singly linked list, return the middle node of the linked list.

Given a string s, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Given an array, rotate the array to the right by k steps, where k is non-negative.

Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. ...

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.