问题：
在一个漆黑的夜晚，有4人带领一个小型桥梁大陆(Continental)已知桥只能容纳两个在同一时间的推移人，桥梁还必须揭示了火炬，但他们只带来了手电筒，对桥的车速四是不一样的，即1分钟，2分钟，5分钟，8分钟。请问如何才能用最短的时间内到达对方。

答：
我会回答。
假设4人甲，乙，丙，D.很明显，两人开始拿着手电筒上桥，在桥的另一边手电筒，现在需要在这两个男人一桥，然后返回桥一侧的手电筒。发送手电筒了跨越的桥梁，而且时间，因此，选出一个更快的增长。
是很自然的想法是，每一次，因此最快阿陪同另一座桥，然后快速跑回A，然后陪同下，在过去的一个，没有人能越过桥上。让我们计，这应该是长。为方便起见，我们旅行(Safari)者的这一桥梁的一面，“这是已知的副作用，开始”时，旅客要到达另一边是被称为“另一边。”在桥的程序表达，我们使用“←”代表与“→”说，从海岸到海岸的运动，从本岸的另一边运动。在前面的“过河阿护送我们，”该程序可以写为：（关于需要完成这一步的时候右图）
抗体→2
甲1
交流←→5
阿←1
广告→8
是2 1 5 1 8 = 17分钟个。

不过，其实有更快的方法：
抗体→2
阿←1
光盘→8
乙2
从头←→2
1 2 1 8 2 +2 = 15分钟。这个聪明的做法是让两个走在在桥上的人最慢，因此花费的时间就是最慢的人去花时间，慢时代谁不需要花费其他桥梁的时间。你可以把所有可能的程序重新上市，他们会发现这是最快的程序

答：
1。 1分钟，2{dy}分钟。时间为2分钟。
2。 1芬中有手电筒回来。了1分钟。
3。 5分钟，8手电筒回到过去分钟。参加8分钟
4。 2分钟后的手电筒。时间为2分钟。
5。 1分钟，2分钟的过去。时间为2分钟。

2芬中八分钟+ 2分钟+ 1分钟+ 2分钟= 15分钟。

There brains problem.

Question:
On a dark night, there are four people to lead a small bridge to the mainland, known to the bridge can only accommodate two people at the same time passed, the bridge must also bring to light the torch, but they only have brought a flashlight, four of the speed of the bridge is not the same, namely, 1 minute, 2 minutes, 5 minutes, 8 minutes. How can I ask to use the shortest time to reach the other side.

Answer:
I ll answer it.
assumed that four were A, B, C, D. Obviously, the two began holding a flashlight across the bridge, the flashlight on the other side of the bridge, and now need to have the bridge in one of those two men then returned to the bridge side flashlight. Send flashlight back across the bridge but also of time, so to elect a gain on faster.
a very natural idea is that every time so that the fastest A accompanied another bridge, and then quickly ran back to A, and then to accompany the next one in the past, nobody can cross the bridge on the. Let us count if this should be long. For convenience, we have travelers starting on this side of the bridge, known as this side of the, while the travelers want to reach the other side is called the other side. In the expression of a bridge program, we use the ← to represent the movement from the other side of this shore, with → said the movement from shore to shore. In front of A to escort us across the river, the program can be written as: (on the right figure for the time required to complete this step)
A B → 2
A ← 1
A C → 5
A ← 1
A D → 8
is a total of 2 +1 +5 +1 +8 = 17 minutes.

However, there are actually a faster way:
A B → 2
A ← 1
C D → 8
B ← 2
A B → 2
a total of 2 +1 +8 +2 +2 = 15 minutes. This clever approach is to let two go at the slowest of the people at the bridge, so that the time spent is just go the slowest person to spend time, and go slow times who do not need to spend time on the other bridge the. You can put all the possible programs are listed again, they will find it is the fastest program of the

Answer:
1. 1 minute, 2 minutes of the first. Took 2 minutes.
2. 1 Fen Zhong with flashlight back. Took 1 minute.
3. 5 minutes, 8 minutes with a flashlight back to the past. Took 8 minutes
4. 2 minutes of flashlight back. Took 2 minutes.
5. 1 minute, 2 minutes of the past. Took 2 minutes.

2 Fen Zhong +8 minutes + 2 minutes + 1 minute + 2 minutes = 15 minutes.04-12-20