用 Scheme 来解决八皇后问题。八皇后问题：在 8*8 的棋盘上放置彼此不受攻击的 8 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意斜线上的棋子。找出所有合法的 使8 个皇后 彼此不受攻击的放置方法。1 ）除了完成 queens 的定义之外 ， 给出一个打印输出过程 print-queens-Scheme used to solve the problem of the eight Queen' s. 8 Queen' s problem: In the 8* 8 chessboard without attacking each other to place the 8 Queens. In accordance with the rules of chess with the Queen can attack in the same column or row, or agreed to slash the piece. To identify all the legitimate Queen of eight so that each placement method against attacks. 1) In addition to the completion of the definition of queens are given a printout of the process of print-queens