传递消息

ob · 发表于 2006-10-24 09:22:33

假设100个人中的每个人都知道1条消息，而且他们所知道的这100条消息都不相同。为了使这100个人都能知道全部消息，他们至少要打多少个电话？

dooggy · 发表于 2006-10-25 06:08:01

99+98+97+96...+3+2+1
because the first person will call everyone but himself, then the second person only needs to call 98 people because the first person already called him (and so on). adding everything together will be 5050, and that is the number of calls to make.

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ob · 发表于 2006-10-25 09:15:47

Can be less

花心石 · 发表于 2006-10-25 12:45:48

Is there a condition that every call can only transfer one message?

If not, the minimum value must <= 197

step 1: person number 2~100 call person number 1 (99 calls), then person number 1 & 100 know all 100 messages.

step 2: person number 1 call person number 2~99 (98 calls), then all know 100 messages.

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ob · 发表于 2006-10-26 04:09:53

漂亮

dooggy · 发表于 2006-10-26 06:22:00

i don't get this.
person number 2~100 call person number 1 (99 calls), then person number 1 & 100 know all 100 messages.
how did person number 100 know all 100 messages?

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dooggy · 发表于 2006-10-26 06:22:55

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ob · 发表于 2006-10-26 07:13:11

The key point here is that one can tell all the messages that he knows to another in one call. The topic is misleading...

花心石 · 发表于 2006-10-26 09:41:11

Here assume number 100 is the 99th call to number 1. When he calls, number 1 have already got message 1~99. On this call, number 100 give number 1 message number 100, number 1 give message 1~99 to number 100

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传递消息

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Can be less[;)]

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