Puzzleup 2019 (08) SIT AND STAND - 拼圖

題目網址: http://www.puzzleup.com/2019/
http://www.puzzleup.com/2019/puzzle/?08
答題時限: 09月12日７ＰＭ－比賽結束
加分時限: 09月12日７ＰＭ－09月18日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　　

◆SIT AND STAND

In a meeting there are 32 participants around a round table, some are
sitting, and some are standing. Every hour there will be a new session.
In each session participants will behave according to the following rule:

-The participants whose neighbors in the previous session being in the
same state will sit, and the participants whose neighbors being in the
opposite state will stand up.

What is the minimum number of sessions needed to guarantee that everyone
will be sitting at the table?

If the problem was asked for 4 people, the answer would be 3.
Example: If the positions are A,A,A,B in the first session, it will be
B,A,B,A in the second session, and A,A,A,A in the third session.
(A: sitting, B: standing)

在一場聚會中，有32位參與者圍繞著一個圓桌，或站或坐。每個小時會進行新的活
動。每次活動參與者將依據以下規則行事：

- 參與者的左右鄰居如果在上個活動同為站起或同為坐下，則參與者將會在新活動
坐下；而如果左右鄰居當時是一站一坐的話，則參與者將在新活動站起來。

問至少要第幾次活動，才能保證每個人都是坐下的？

如果問題是問四個人的話，答案會是3次活動。

例：如果首動是A,A,A,B,將第二動會是B,A,B,A,第三動為A,A,A,A。(A:坐著，B:站著)

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