Single number · Q25:Given a non-empty array of integers nums, every element appears twice except for one. Find that single one. You must implement a...

Rat in a maze · Q24:Consider a rat placed at (0, 0) in a square matrix of order N * N. It has to reach the destination at (N - 1, N - 1). Find all...

N Queens · Q23:The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other. Given an integer...

Letter combination of a phone number · Q22: Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number...

Combination II · Q21:Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where...

Combination Sum · Q20:Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates...