Robina Li

You are given a 2D array of axis-aligned rectangles. For each rectangle[i] = [xi1, yi1, xi2, yi2], where (xi1, yi1) is the bottom-left corner and (xi2, yi2) is the top-right...

You are given an m x n grid rooms initialized with these three possible values:

Given an integer n, return the least number of perfect square numbers that sum to n.

Greedy algorithms are among the most elegant tools in competitive programming — when they work, they’re simpler and faster than dynamic programming. This guide covers the core greedy patterns you’ll...

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

You are given an m x n grid where each cell can have one of three values:

Given an array of meeting time intervals intervals where intervals[i] = [starti, endi], return the minimum number of conference rooms required.

Given two binary strings a and b, return their sum as a binary string.

Given two 1d vectors, implement an iterator to return their elements alternately.

Design a Skiplist without using any built-in libraries.