Can you solve the killer robo-ants riddle? - Dan Finkel

翻译人员: Leonard Au 校对人员: Lipeng Chen

The good news is that your experimental robo-ants

好消息是，你的机器蚁实验成功了。

are a success!

The bad news is that you accidentally

坏消息是，

你不小心赋予了它们发射致命激光的能力，

just gave them the ability to shoot deadly lasers

…and you can’t turn it off.

却又无法把它关掉。

You have five minutes to stop them

你有五分钟的时间

before the lasers go online.

在激光系统启动之前制止它们。

Until then,

all of your robo-ants will walk

在此之前，所有机器蚁会在窝里行走，

inside their habitat at a speed of

exactly 1 meter per minute.

速度为每分钟一米。

If they bump into each other or hit a dead end,

要是迎面碰上，或者走到了死胡同，

they’ll instantly turn around

它们立刻就会转身，

and walk back the way they came.

往原来的方向走回去。

When five minutes are up,

五分钟一到，它们就会启动激光，

they’ll turn on their lasers,

break free,

逃出蚁窝，往外流窜，

and stream out into the world,

carving a path of destruction as they go.

走到哪里，摧毁哪里。

Your one chance to stop them is to insert

制止它们的唯一机会，

就是将两条紧急真空吸嘴插进蚁窝，

the two emergency vacuum nozzles into the habitat

and suck the ants up before they break free.

在蚂蚁逃脱之前把它们吸走。

The nozzles can press into any one location

吸嘴可以插进蚁窝的任何位置，

in the habitat through a membrane covering

只需穿破前面的膜就可，

its front side, and any ants that walk past

蚂蚁只要经过吸嘴，

will be sucked up and deactivated.

就会被吸走并且被解除。

You can’t move the nozzles once they’re placed

吸嘴插入蚁窝后就不能再移动，

without leaving a hole that the robo-ants

不然会留下洞口，让机器蚁大量涌出。

would pour out of, so choosing the

所以，选择正确的位置非常重要。

right spots will be key.

The habitat is made out of meter-long tubes.

蚁窝由一米长的管制作而成。

When the robots reach an intersection,

蚂蚁一走到交叉口，

they will pick randomly whether to go

就会随机选择往左、往右或往前走。

left, right, or forward.

They only go backward if they hit

他们只有在碰到另一只机器蚁

hit another robo-ant or a dead end.

或者走到死胡同时才转头。

Unfortunately, there are hundreds of them

不幸的是，蚁窝里有数百只蚂蚁，

inside the habitat, and if even one escapes,

就算只有一只蚂蚁逃脱，

it’ll do a lot of damage.

它也会造成很大的破坏。

With just less than five minutes remaining,

现在只剩下少过五分钟，

where should you place the 2 vacuum nozzles

两个真空吸嘴应该插在哪里，

to suck up all the robo-ants?

才能把所有机器蚂蚁吸掉？

Pause the video now if you want to figure it out for yourself.

（如果要自己想答案，请现在暂停视频！）

Answer in: 3

Answer in: 2

Answer in: 1

With robo-ants ricocheting all over the habitat,

机器蚁在蚁窝里到处流窜，

it might seem impossible to stop them

趁它们逃脱之前制止它们，

before they break free.

好像是不可能的事情。

But this situation is simpler than it seems.

但是这个状况比想象中更简单。

Here's why.

为什么呢？

Imagine just two robo-ants crawling

想象两只机器蚁相向而行。

toward each other.

When they collide, they immediately

它们一碰撞，就会立刻转身。

reverse directions.

And what would that sequence of events look

如果它们只是经过彼此的话， 情况会怎样呢？

like if they crawled past each other instead?

It would look exactly the same before

不管是在碰撞前后都一样，

and after their collision, but with

their positions swapped.

只是两只蚂蚁的位置对调了。

This is true every time a pair of robo-ants meet.

只要有两只机器蚁相遇，情况都一样。

Because the identities of individual ants

个体蚂蚁的身份不重要，

don’t matter, you just need to figure out where

所以你只需要找出正确的插吸嘴位置，

you should put the nozzles to capture

在少于5分钟的时间内，捕捉到每一只不停行走的蚂蚁，

any single ant walking without interruption

for less than 5 minutes, starting from

不管它从蚁窝里的什么位置开始行走。

any point in the habitat.

That’s much easier to conceptualize and solve.

有了这个概念，问题就更容易解决了。

Placing the nozzles at intersections where

把吸嘴放在三、四条管的交叉口，

three or four tubes meet seems like your best bet

可能就是最佳选择，

since that’s where the robo-ants might otherwise

因为机器蚁可能会在这里换方向，

change directions and miss your nozzles.

从而躲避了你的吸嘴。

There are only four intersections…

交叉口只有四个，

which two should you pick?

你该选择哪两个呢?

The top right intersection has to be one of them.

右上方交叉口必须是其中一个，

If it isn’t, an ant crawling down from

要不然，如果蚂蚁从这里走向死胡同，

this intersection toward the dead end would

crawl for four minutes to get back to the

它爬行四分钟后将会回到交叉口，

intersection, and then go in any of three

然后从三个方向中选择一个，

directions, walking for at least another minute.

继续行走至少一分钟。

Once you’ve placed a nozzle in the top right,

一旦在右上方插入了吸嘴，

the only other choice that has a chance

就只剩下一个有效的选择，

to work is the bottom left.

就是左下方交叉口。

To see that this works, imagine an ant

为了证明这样有效，

想象一下蚁窝内任何位置的一只蚂蚁。

anywhere else in the habitat.

Worst case scenario, the ant would start

最糟的情况下，蚂蚁从吸嘴旁边开始，

right next to the vacuum nozzle, marching away from it.

背对着吸嘴行走。

But in all those worst cases, the ant would march

但是就算在这些情况下，

蚂蚁爬行最多四米后，

for at most 4 meters before being sucked

就会被真空吸走。

up into the vacuum.

No other choice of two intersection points

除这两个交叉口的组合之外，

is guaranteed to get all the robo-ants

其它组合都无法保证 能在五分钟内吸走所有蚂蚁。

within five minutes.

Having vacuumed them all up, you’ve

吸掉了所有蚂蚁，就化解了一次重大危机。

averted a major crisis.

Before you mess with robo-ants again,

下次再玩机器蚂蚁之前，

you’ll want to have a robo-anteater ready.

最好先准备一只机器食蚁兽。

And wouldn’t it be cool if it could

要是它能飞、能喷火，那该有多酷！

fly and breathe fire?

There’s no way that could go wrong!

这样就不会出问题了！