Five Watchman Bridge Crossing Puzzle | MindYourLogic Bridge Crossing Puzzle

Five watchmen need to cross a moonlit bridge at night using only one lantern. Each watchman moves at a different speed, and the bridge can hold at most two watchmen at a time. The goal is to find the minimum total time required for all five watchmen to cross the bridge, which is 29 minutes. This puzzle requires careful planning to optimize the crossing times while managing the lantern efficiently.

Conditions:

Watchman A: 1 minute
Watchman B: 2 minutes
Watchman C: 5 minutes
Watchman D: 8 minutes
Watchman E: 13 minutes

Objective:
Determine the minimum time required for all five watchmen to cross the bridge.

Steps to Cross the Bridge in Minimum Time:

First Crossing:

Watchman A (1 minute) and Watchman B (2 minutes) cross the bridge together.
Time taken: 2 minutes (the time of the slower watchman, Watchman B).
Lantern Return:

Watchman A (1 minute) returns with the lantern.
Time taken: 1 minute.
Total time elapsed: 3 minutes.

Second Crossing:

Watchman D (8 minutes) and Watchman E (13 minutes) cross the bridge together.
Time taken: 13 minutes (the time of the slower watchman, Watchman E).

Lantern Return:

Watchman B (2 minutes) returns with the lantern.
Time taken: 2 minutes.
Total time elapsed: 18 minutes.

Third Crossing:

Watchman A (1 minute) and Watchman C (5 minutes) cross the bridge together.
Time taken: 5 minutes (the time of the slower watchman, Watchman C).
Total time elapsed: 23 minutes.

Final Lantern Return:

Watchman A (1 minute) returns with the lantern.
Time taken: 1 minute.
Total time elapsed: 24 minutes.

Final Crossing:

Watchman A (1 minute) and Watchman B (2 minutes) cross the bridge together again.
Time taken: 2 minutes (the time of the slower watchman, Watchman B).
Total time elapsed: 26 minutes.

Conclusion:
By following this strategy, all five watchmen will cross the moonlit bridge in a total of 26 minutes. The strategy effectively manages the lantern and balances the crossing times of the watchmen to achieve the minimal total crossing time.