Given an array A of non-negative integers, half of the integers in A are odd, and half of the intege...

Given a string S, return the "reversed" string where all characters that are not a letter ...

In a deck of cards, each card has an integer written on it. Return true if and only if you can choos...

Given an array A of integers, for each integer A[i] we may choose any x with -K <= x <= K, and...

Given an array A of non-negative integers, return an array consisting of all the even elements of A,...

Given a binary search tree, rearrange the tree in in-order so that the leftmost node in the tree is ...

An array is monotonic if it is either monotone increasing or monotone decreasing. An array A is mono...

Alice and Bob have candy bars of different sizes: A[i] is the size of the i-th bar of candy that Ali...

We are given two sentences A and B. (A sentence is a string of space separated words. Each word cons...

Given a non-empty, singly linked list with head node head, return a middle node of linked list. If t...