# BBO Discussion Forums: 推理问题 - BBO Discussion Forums

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## 推理问题 与桥牌无关

• China
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Posted 2013-November-25, 18:08

bill兄弟两和父母一起要在深夜过一桥。

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• China
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Posted 2013-November-25, 18:11

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### #3lycier

• AlphaBridge
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Posted 2013-November-27, 04:52

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### #4dvd

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Posted 2013-November-29, 04:54

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### #5bgm

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Posted 2013-November-29, 06:15

dvd's attempt is a very natural one. One can easily see that the pattern will be

2 members forward -> 1 member backward -> 2 members forward -> 1 member backward -> 2 members forward

and to minimize the backward time, we will assign Bill as the man holding the torch and accompany all his family members forward. This will result in dvd's answer.

However, we shall note that there is clear wastage when Bill bring his parents forward in the above design. There will be less wastage when both parents go forward together. Namely,

Two Brothers forward (3) -> Bill backward (2) -> Parents forward (8) -> Brother backward (3) -> Two Brothers forward (3)

and the result will be only 19 mins. Note the order of backward can be exchanged in this design.
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• China
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Posted 2013-December-01, 20:51

bgm, on 2013-November-29, 06:15, said:

dvd's attempt is a very natural one. One can easily see that the pattern will be

2 members forward -> 1 member backward -> 2 members forward -> 1 member backward -> 2 members forward

and to minimize the backward time, we will assign Bill as the man holding the torch and accompany all his family members forward. This will result in dvd's answer.

However, we shall note that there is clear wastage when Bill bring his parents forward in the above design. There will be less wastage when both parents go forward together. Namely,

Two Brothers forward (3) -> Bill backward (2) -> Parents forward (8) -> Brother backward (3) -> Two Brothers forward (3)

and the result will be only 19 mins. Note the order of backward can be exchanged in this design.

Excellent!You are right!
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