一个过河游戏的简单例子，描述：将猫和狗还有老鼠运送到河对岸，要求，一次只能携带一只动物，且猫和老鼠不能共存，猫和狗也不能共存。使用最少的步骤完成-A simple example of the game across the river to describe: The cats and dogs are transported to the side of the river rats, the requirements can only carry one animal, and Tom a