The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens
attack each other.
Given an integer n, return all distinct solutions to the n-queens puzzle.
Each solution contains a distinct board configuration of the n-queens’ placement, where ‘Q’ and ‘.’
both indicate a queen and an empty space respectively.
For example, There exist two distinct solutions to the 4-queens puzzle:
[
[“.Q..”, // Solution 1
“…Q”,
“Q…”,
“..Q.”],
[“..Q.”, // Solution 2
“Q…”,
“…Q”,
“.Q..”]
]