此程序源码为回溯算法中的n后问题，可以根据需要更改棋盘大小。已加入时间函数，可以分析不同棋盘规模下的运行时间。-This procedure for the backtracking algorithm source of n after the problem may be based on need to change the board size. Has joined a function of time, can be analyzed under a different board