Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in th...

Design a simplified version of Twitter where users can post tweets, follow/unfollow another user and is able to see the 10 most recent tweets in the user’s news...

Given n balloons, indexed from 0 to n-1. Each balloon is painted with a number on it represented by array nums. You are asked to burst all the balloons. If the ...

A frog is crossing a river. The river is divided into x units and at each unit there may or may not exist a stone. The frog can jump on a stone, but it must not...

X city built a new stadium, each day many people visit it and the stats are saved as these columns: id, visit_date, people

Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region.

CIA has decided to create a special telephone directory for its agents. The first 2 pages of the directory contain the name of the directory and instructions fo...

You are climbing a stair case. It takes n steps to reach to the top.

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.

Given an array of non-negative integers, you are initially positioned at the first index of the array.