Four Opretors Bridge Crossing Puzzle | MindYourLogic Bridge Crossing Puzzle

In this classic puzzle, four bridge operators with different crossing speeds need to cross a narrow bridge at night using only one lantern. Each operator's crossing times are as follows: Operator A takes 2 minutes, Operator B takes 3 minutes, Operator C takes 6 minutes, and Operator D takes 7 minutes. The challenge is to determine the minimum total time required for all operators to cross the bridge, given that they can only cross one at a time with the lantern. The optimal solution for this puzzle requires a total of 18 minutes.

Steps to Solve:

Initial Crossing:

Operator A (2 minutes) and Operator B (3 minutes) cross the bridge first.
Time taken: 3 minutes (the time of the slower operator, Operator B).
Total time so far: 3 minutes.

Lantern Return:

Operator A (2 minutes) returns with the lantern.
Time taken: 2 minutes.
Total time so far: 5 minutes.

Second Crossing:

Operator C (6 minutes) and Operator D (7 minutes) cross the bridge together.
Time taken: 7 minutes (the time of the slower operator, Operator D).
Total time so far: 12 minutes.

Lantern Return:

Operator B (3 minutes) returns with the lantern.
Time taken: 3 minutes.
Total time so far: 15 minutes.

Final Crossing:

Operator A (2 minutes) and Operator B (3 minutes) cross the bridge again.
Time taken: 3 minutes (the time of the slower operator, Operator B).
Total time so far: 18 minutes.

Conclusion:
By following these steps, all four bridge operators successfully cross the narrow bridge with a minimum total time of 18 minutes. This solution ensures that the lantern is efficiently used, and all operators reach the other side without any delays.