The Crossing the Bridge puzzle is a classic logic puzzle that goes as follows:
Four people need to cross a bridge at night. They have only one torch and the bridge is too dangerous to cross without it. The bridge can only hold two people at a time. The four people take different amounts of time to cross the bridge: one person takes 1 minute, another takes 2 minutes, the third takes 5 minutes, and the fourth takes 10 minutes. When two people cross the bridge together, they must go at the slower person’s pace. What is the shortest time that all four people can cross the bridge?
Crossing the Bridge Puzzle solution
To solve this puzzle, we need to use a combination of trial and error and logic. Here is one possible solution:
- The two fastest people (1 minute and 2 minutes) cross the bridge together. It takes them 2 minutes.
- The fastest person (1 minute) returns to the starting side of the bridge, which takes him 1 minute.
- The two slowest people (5 minutes and 10 minutes) cross the bridge together. It takes them 10 minutes.
- The second fastest person (2 minutes) returns to the starting side of the bridge, which takes him 2 minutes.
- The two fastest people (1 minute and 2 minutes) cross the bridge together for the second time. It takes them 2 minutes.
Total time taken: 2 + 1 + 10 + 2 + 2 = 17 minutes.
Therefore, the shortest time that all four people can cross the bridge is 17 minutes.
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