In the classic bridge-and-torch puzzle with times 1, 2, 7, and 10 minutes, what is the minimum total time to get everyone across?

A hard logic questions prompt from the quest1on archive. Try it first, then compare your answer with the explanation and related questions below.

Explanation

The efficient solution is 1 and 2 cross, 1 returns, 7 and 10 cross, 2 returns, then 1 and 2 cross again. That totals 17 minutes.

Did you know?

This puzzle is famous because the fastest person should not always escort every crossing. The key is using the two quickest people as the return team.

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