The N-Queens problem is a classic backtracking problem in computer science, where the goal is to place N queens on an NxN chessboard such that no two queens attack each other.
Given an integer n , return all possible configurations of the board where n queens can be placed without attacking each other.
The space complexity of the solution is O(N^2), where N is the number of queens. This is because we need to store the board configuration and the result list.