rescue 孤岛营救问题 大兵瑞恩被关押在迷宫的东南角，即(N，M)单元里，并已经昏迷。迷宫只有一个入口，

在西北角。也就是说，麦克可以直接进入(1，1)单元。另外，麦克从一个单元移动到另一个

相邻单元的时间为1，拿取所在单元的钥匙的时间以及用钥匙开门的时间可忽略不计。-island to rescue Private Ryan, rescue issues to be held in the southeast corner of the maze, namely (N, M) unit in, and has been unconscious. Labyrinth has only one entrance, in the northwest corner. That is, Mike can go directly to (1,1) unit. In addition, Mike moved from one cell to another adjacent cell for 1, where the unit pick up the keys to open the door with a key time and time is negligible.