n Queens problem LeetCode 51

The n-queens problem is a well-known problem in computer science and mathematics that involves placing n chess queens on a n x n chessboard such that no two queens are able to attack each other. This means that no two queens can be placed on the same row, column, or diagonal. The problem can be generalized to other chess pieces, such as the n-rooks problem (where the goal is to place n rooks on the board such that no two rooks can attack each other) or the n-knights problem (where the goal is to place n knights on the board such that no two knights can attack each other). The n-queens problem is often used as a test case for algorithms that solve combinatorial search problems, as it is a challenging problem that requires careful consideration of the constraints and the search space. There are several ways to solve the n-queens problem, including backtracking algorithms, constraint satisfaction algorithms, and heuristic search algorithms. In LeetCode, the n-queens problem is represented as problem 51 and can be found at the following link: https://leetcode.com/problems/n-queens/. The problem asks the user to implement a function that takes in an integer n and returns a list of all valid configurations of n queens on an n x n chessboard. The function should return an empty list if no valid configurations exist.