最短步数算法，拼图游戏的最原始版本，中间的next按钮按第一次的时候是计算返回到出事状态的步骤。之后每按一次，便倒着走回去（最少步数）。有代码、有注释、有运行结果图。-The algorithm of the shortest number of steps, the most primitive version of the jigsaw puzzle, the first time, the middle of the next button is to calculate the return to the accident the steps of the state. After each time you press, then backwards to go back (at least the number of steps). Code, comments, and operating results in Figure.