N-Queens

Statement

Given a chessboard of size $n \times n$, determine how many ways $n$ queens can be placed on the board, such that no two queens attack each other.

A queen can move horizontally, vertically, and diagonally on a chessboard. One queen can be attacked by another queen if both share the same row, column, or diagonal.

Constraints:

• $1 \leq n \leq 9$

Examples