 |  | | The problem of crossing bridge |
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 發表於: 星期三 十月 31, 2007 8:32 pm |
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| kim |
| 敬拜者 |
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| 註冊時間: 2007-07-29 |
| 文章: 161 |
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Assume there are 4 people , A, B, C and D, need to cross a bridge. The night is dark and they have only one flash light. to make the situation worse, the bridge can only carry 2 people at one time. Thus, whenever 2 people cross the bridge, one person always has to go back to bring other people over (because they have only one flash light, remember!)
Now, A can cross the bridge at 5 min
B can do it in 2 min
C can do it in 10 min
D can do it in 1 min
when 2 people cross the bridge at same time, they always have to move at the slower pace. (if A and C walk together, it will take them 10 min to cross).
Q: what's the most efficient way to bring all 4 people over? |
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| 發表於: 星期三 十月 31, 2007 8:35 pm |
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| kim |
| 敬拜者 |
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| 註冊時間: 2007-07-29 |
| 文章: 161 |
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| HInt : the answer is not the obvious solution which takes 19 min !! |
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| 發表於: 星期三 十月 31, 2007 8:39 pm |
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| kim |
| 敬拜者 |
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| 註冊時間: 2007-07-29 |
| 文章: 161 |
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btw.. dont see much going on with the forum these days...
c'm on.. give this a shot!
it's a do-able problem, just take some thinking beyond intuition |
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| 發表於: 星期三 十月 31, 2007 9:41 pm |
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| Mikka |
| 天使長 |
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| 註冊時間: 2007-07-20 |
| 文章: 129 |
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| kim 寫到: |
btw.. dont see much going on with the forum these days...
c'm on.. give this a shot!
it's a do-able problem, just take some thinking beyond intuition |
17minutes!!! |
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_________________
"你给我扁一顿，你就不空虚了我也就不烦躁了" - Pipi |
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| 發表於: 星期三 十月 31, 2007 10:00 pm |
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| kim |
| 敬拜者 |
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| 註冊時間: 2007-07-29 |
| 文章: 161 |
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