组合分析 - 多少个小猫咪咪？(revised 1.0)

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在英国有好几个地方叫 St. Ives 的，这张是其中的一个博物馆顶楼照的。 （点击图片见更多信息）

   当塞翁被唤作塞青还是在念博士课程的时候，要选四门功课作为获取博士候选生资格的考核课题，并分别在连续的四天内，至少通过其中的两门否则全部作废。塞青所选课题，包含一门基础概率，用的是南加大 Sheldon Ross 教授的 《A First Course In Probability》；凭着中学微薄的一点高等数学基础，挑灯夜战，勉强过关。

   记得 Ross 教授在第一章中给出的一道组合习题很简单，用不着组合概念，也很有意思；它要求从一首童谣 (nursery rhyme) 讲的故事，计算出有多少个小猫咪咪。塞翁把那本书找出来了，将那首童谣的开始部分抄录如下，并想看看大家能否在念完童谣之后的半分钟之内将答案或算法列出来。不过注意了，尽管叫作童谣，还是不适合念给家里小朋友的噢...：
  
   As I was going to St. Ives 
   I met a man with 7 wives.
   Each wife had 7 sacks.
   Each sack had 7 cats.
   Each cat had 7 kittens.
   How many kittens did the traveler meet?

   好了，念完了吧？

   别忘了要 post your solution here... 
   
   Bye-bye... and see you next time!

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A little more on St. Ives, and listen for the words that'd be pleasing the ear...(点击此处，and listen for English's English.)

There are two other versions of the nursery rhyme in publications...

The first version:

As I was going to St Ives

I met a man with seven wives

         And every wife had seven sacks
         And every sack had seven cats
         And every cat had seven kits

         Kits, cats, sacks, wives
         How many were going to St Ives?

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The second version:

As I was going to St Ives

I met a man with seven wives

Seven wives with seven sacks

Seven sacks with seven cats

Seven cats with seven kits

Kits, cats, sacks, wives

How many were going to St Ives?


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