赛马

ob · 发表于 2005-6-3 04:33:16

There are 25 horses. And there is only one racing track. This racing track can only race at most five horses at a time. Assume that you do not have timer. You can only determine which horse run faster by your eye. Also assume that each horse always run the same constant speed (yes, if the horse run 10mph, then it will always stay constant at 10mph) and no two or more horses run the same speed (yes, none of them will tie). How many times (fewest possible) do you need to race to get the fastest 3 horses?

husonghu · 发表于 2005-6-9 12:09:58

共7次：

先是25马分成五组跑：A、B、C、D、E，每组5马。记每组名次排列：A1、A2、...
B1、B2、...等等。共赛5次。

第6次，将每组的第一名A1、B1、C1、D1、E1跑，得出前三名，假设这前三名依次是
A1、B1、C1。

A1定是总计第一。总计第二第三必在A2、A3、B1、B2、C1这5马当中。故第7次，将
这5马跑，找出前两名即可。

ob · 发表于 2005-6-10 03:37:57

old friends. I see Jenny, 红罂粟 and several new friends around only. Maybe it's time for you to come to host this forum together with新用户now. I looked different forums and really amazed by 新用户's great efforts and capabilities to contribute 顶顶华闻. I sugget you come out to help him in this forum. As usual, Jenny and I will keep supporting both of you

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赛马

唉，此坛最近冷清啊！高手们都哪去了呢？怎么我忙，大家也忙啊？试答.

Nice and clear! I don't know where are those