Given n non-negative integers representing an elevation map where the wi...

You have 4 cards each containing a number from 1 to 9. You need to judge...

You are given a data structure of employee information, which includes t...

Implement the following operations of a queue using stacks. push(x) -- P...

Remove the minimum number of invalid parentheses in order to make the in...

Given an integer matrix, find the length of the longest increasing path....

Given a non-empty 2D array grid of 0's and 1's, an island is a group of ...

The thief has found himself a new place for his thievery again. There is...

Given an integer, write a function to determine if it is a power of two....

Given a binary search tree, write a function kthSmallest to find the kth...