用回溯法求马周游问题,马在棋盘上走字步,从马开始的位置开始周游棋盘,遍历全棋盘后回到起点,是否可行,可行的就输出路径,路径并输入尝试过的路径数,跳过的路径数-law with retrospective travel for Ma, Ma on the chessboard characters step away from the start position Ma started to travel around the chessboard, traverse the whole chessboard return to the starting point and feasible, and viable on the output path, path and enter the path tried a few, the path to skip a few