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 ~n~, return /all distinct solutions to the *n-queens puzzle*/. You may return the answer in *any order*.
Each solution contains a distinct board configuration of the n-queens' placement, where ~'Q'~ and ~'.'~ both indicate a queen and an empty space, respectively.