Tuesday, March 27, 2007

Riddles and Thinkers

Question: Every man in a village of 100 married couples has cheated on his wife. Every wife in the village instantly knows when a man other than her husband has cheated, but does not know when her own husband has. The village has a law that does not allow for adultery. Any wife who can prove that her husband is unfaithful must kill him that very day. The women of the village would never disobey this law. One day, the queen of the village visits and announce that at least one husband has been unfaithful. What happens?

In logically thinking...

Lets say n is the number of cheaters. Some wifes think there are n cheaters and some wifes think there are n-1 cheaters as they assume their husbands are innocent.

If n = 1, the wife who thinks the number of cheaters are zero. She will kill her husband when the queen announces at least one.

If n = 2, some wifes will know number of cheaters are 2 and some wifes will know number of cheater is 1. In the first (1) day, the wife who knows the number of cheater is 1 will not sure whether her husband is cheater or not. In the second (2) day, if no one kill their husbands and it implies her own husband is the cheater.

In conclusion, in n th day, the cheaters will be killed by their wifes.

From inner thinking, I will kill my own husband in the very first day. In Chinese, it is so called "kill 1 alert 100". ;)

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