有15个编有1至15数码的棋子，放在4×4方格棋盘上，还有一个空格，空格周围的棋子可以向空格移动。初始棋局（图一）和目标棋局（图二）如下-There are 15 series have a digital 1-15 pawn on the 4 × 4 chessboard grid, there is a space, spaces around the pawn can move to the space. The initial game (Figure 1) and target gam