笔者曾经看到过一道智力题(具体来源记不清了),大体意思是这样的:甲要把一面红旗插到一个沙漠中的某一点,然后返回出发地。从出发地到目的地需要走4天的时间。因为甲只能带5桶水(1天用1桶水),而他从出发到返回原地需要行走8天的时间,所以需要招募一些志愿者为其补充用水。假设志愿者每人都只能带5桶水,而且每人每天都需要1桶水,那 I have seen an intellectual question (the specific source can not remember), the general meaning is this: A red flag should be inserted to a point in the desert, and then return to the starting place. It takes 4 days to travel from the destination to the destination. Because A can only take 5 buckets of water (1 bucket of water a day) and he needs to walk for 8 days from the start to return, some volunteers need to be recruited to replenish it. Suppose volunteers can only bring 5 barrels of water per person, and each of them needs 1 bar of water per day