在n×n格的棋盘上放置彼此不受攻击的n个皇后，按照国际象棋的规则，皇后可以攻击与之处在同一行或同一列或同一斜线上的棋子，求解可以放置的方法种数。-Placed on the n × n chessboard grid attack each other n-queens, in accordance with the rules of chess, the queen can attack in the same row or column, or diagonal pieces of the