[問題] 用骰子選人當鬼
看板puzzle (益智遊戲 - 數獨,拼圖,推理,西洋棋)作者DreamYeh (天使)時間12年前 (2012/11/29 12:40)推噓29(29推 0噓 36→)留言65則, 16人參與討論串1/10 (看更多)
這是我和小朋友教學時候實際遇到的問題,實際上當時沒有得到一個滿意解答
因此來挑戰一下大家頭腦!希望能集思廣益,得到一個最好答案
問題是這樣子的:
有七個小朋友,要"公平"選出一個人出來當鬼
我們有一顆骰子,可以公平擲出1~6,但我們有七個人啊!
在不借用其他工具下,請提出最佳策略,可以擲最少次骰子來選出一個鬼。
記得~如果你的策略需使用的次數不一定,你需要算個期望值出來比較!
比方說一個直覺策略是這樣:
「每個小朋友各丟一次,選出丟的點數最大的那一位」
但這樣至少也要丟七次,甚至可能要更多次,可以算出個期望值,但無論如何都
不是良好策略
另一方面,你不可以提出個不公平的策略,譬如說:
「丟骰子兩次,將總和加起來,然後除以七看餘數」,是只丟兩次就好,但很容
易證明不公平。
當時和幾個朋友討論,最佳策略是2.xx次,不知是否有人能找出更好的策略呢?
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※ 編輯: DreamYeh 來自: 1.34.96.93 (11/29 12:41)
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