TED-Ed Video Lesson Transcript:
The good news is that your experimental robo-ants are a success!
The bad news is that you accidentally just gave them the ability to shoot deadly lasers… and you can’t turn it off. You have five minutes to stop them before the lasers go online.
Until then, all of your robo-ants will walk inside their habitat at a speed of exactly 1 meter per minute.
If they bump into each other or hit a dead end, they’ll instantly turn around and walk back the way they came.
When five minutes are up, they’ll turn on their lasers, break free, and stream out into the world, carving a path of destruction as they go.
Your one chance to stop them is to insert the two emergency vacuum nozzles into the habitat and suck the ants up before they break free. The nozzles can press into any one location in the habitat through a membrane covering its front side, and any ants that walk past will be sucked up and deactivated.
You can’t move the nozzles once they’re placed without leaving a hole that the robo-ants would pour out of, so choosing the right spots will be key.
The habitat is made out of meter-long tubes. When the robots reach an intersection, they will pick randomly whether to go left, right, or forward. They only go backward if they hit another robo-ant or a dead end.
Unfortunately, there are hundreds of them inside the habitat, and if even one escapes, it’ll do a lot of damage.
With just less than five minutes remaining, where should you place the 2 vacuum nozzles to suck up all the robo-ants?
Pause the video now if you want to figure it out for yourself. Answer in: 3. Answer in: 2. Answer in: 1.
With robo-ants ricocheting all over the habitat, it might seem impossible to stop them before they break free.
But this situation is simpler than it seems.
Here’s why. Imagine just two robo-ants crawling toward each other. When they collide, they immediately reverse directions.
And what would that sequence of events look like if they crawled past each other instead?