23 囚犯問題

看板puzzle (益智遊戲 - 數獨,拼圖,推理,西洋棋)作者weijr (Beware of the Monkey)時間19年前 (2005/05/15 13:17)推噓0(0推 0噓 0→)

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The warden meets with 23 new prisoners when they arrive. He tells them, "You may meet today and plan a strategy. But after today, you will be in isolated cells and will have no communication with one another. "In the prison is a switch room, which contains two light switches labeled A and B, each of which can be in either the 'on' or the 'off' position. I am not telling you their present positions. The switches are not connected to anything. "After today, from time to time whenever I feel so inclined, I will select one prisoner at random and escort him to the switch room. This prisoner will select one of the two switches and reverse its position. He must move one, but only one of the switches. He can't move both but he can't move none either. Then he'll be led back to his cell. "No one else will enter the switch room until I lead the next prisoner there, and he'll be instructed to do the same thing. I'm going to choose prisoners at random. I may choose the same guy three times in a row, or I may jump around and come back. "But, given enough time, everyone will eventually visit the switch room as many times as everyone else. At any time anyone of you may declare to me, 'We have all visited the switch room.' "If it is true, then you will all be set free. If it is false, and somebody has not yet visited the switch room, you will be fed to the alligators." There exists a strategy such that, if the prisoners adopt it, they are guaranteed to be set free (given enough time). What is the strategy? -- http://weijr.b81.org/poker 賭聖的秘密情人 That's No Limit, Baby! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 69.235.31.142