农夫过河问题讲述的是一位农夫带着一只狼，一只羊和一颗白菜要渡过一条河，只有农夫能开船，且每次农夫只能带最多一样东西，并且农夫不在的时候，狼和羊，羊和白菜不能共存，我们需要在这个前提下找到渡河的最短路径。(About the farmer across the river is a farmer with a wolf, a sheep and a cabbage to cross a river, the farmer can only sail, and each farmer can onl