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命运子弹

Bullets of Fate

专题
Probability / 概率
难度
L8

题目详情

房间里有 NN 个持枪者。每到钟声响起,所有人同时随机选择另一个人射击。

被射中的人当场死亡,存活者在下一次钟声继续同样过程。

最终要么全死,要么只剩 1 个幸存者。

问:当 NN\to\infty 时,出现幸存者的概率极限是多少?

备注:原作者也未给出严格证明。

In a room stand NN armed and angry people. At each chime of a clock, everyone simultaneously spins around and shoots a random other person. The persons who get shot, fall dead and the survivors spin and shoot again at the next chime. Eventually, either everyone is dead or there is a single survivor.

As NN grows, what is the limiting probability that there will be a survivor?

Warning: I could not solve it. The solution only shows what I tried.

解析

目前更像是一个“数值观察题”。原作者通过模拟/暴力/动态规划实验发现:该概率似乎趋近于 0.5,但未给出严格证明。

中文侧保留这一结论与限制:只有经验现象,没有证明。


Original Explanation

Solution

I have tried the following scripts

  1. Simulation Script
  2. Brute Forcing Script
  3. Simulation with Dynamic Programming

Following is the pattern.

plot1

plot1

plot1

It appears to be moving towards 0.5 but I do not have any proof or any intuitive logic as to why.

Also, not sure why these waves appeared, and why the wavelength is expanding.