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Then-queens puzzle is the problem of placingnqueens on ann×nchessboard such that no two queens attack each other. Given an integern, return all distinct solutions to then-queens puzzle. Each...

Given a chemicalformula(given as a string), return the count of each atom. An atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name. ...

In a N x Ngridrepresenting a field of cherries, each cell is one of three possible integers. 0 means the cell is empty, so you can pass through; 1 means the cell contains a cherry, that you can...

There is a box protected by a password. The password is a sequence ofndigitswhere each digit can be one of the firstkdigits0, 1, ..., k-1. While entering a password,the lastndigits entered wil...

Specialbinary strings are binary strings with the following two properties: The number of 0's is equal to the number of 1's. Every prefix of the binary string has at least as many 1's as 0's. ...

Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and empty sp...