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A thief has to a cross a river filled with man eating animals, by crossing a bridge to get to a princess with whom he wants to stay for the rest of his life. But on the other side of the bridge is a guard who will chase him back as soon as he is spotted. The guard sleeps for 5 minutes and watches for 10 minutes and the man can cross the bridge in 7 minutes. How can he ever get to the princess at the other side of the bridge without being chased back to the other side?
Even if you would have a blackjack (which the thief has not), you'd have to get to the Guard first. It takes 7 minutes to get there, and he only sleeps for 5 minutes.
That's easy. Let's assume bridge is 70ft. and you can move at a speed of 10ft per minute.
When he falls asleep, start crossing the bridge.
When you're at 50ft. the guard will wake up and starts chasing you.
Now you both run down the bridge, and when you're safe, guard has been running for 5 minutes and is at 20ft.
He then starts going back, but you show up now and then, so he eventually comes closer to your side of the bridge.
After harassing him for five minutes, he'll fall asleep. Now you just creep past him and run to the other side of the bridge.
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Now, you may argue, that the guard won't come chasing after you, and that he'll just shout bad words at you... but then, you'd just walk on the bridge until he falls asleep and walk past him.
If he sleeps for 5 minutes, then watches for 10 minutes, just wait 15 minutes. After that time, he's gone off to do something not specified in the riddle, so how long it takes you to cross the bridge is immaterial.
If he sleeps for 5 minutes, then watches for 10 minutes, just wait 15 minutes. After that time, he's gone off to do something not specified in the riddle, so how long it takes you to cross the bridge is immaterial.
I was gonna say something like that, but that makes little sense. He watches for 10 and sleeps 5? Is that in cycles or something?
TCO – Retired
Former TCO Head of Intelligence – Retired
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