During the war, a small detachment found itself confronted by a deep and wide river. However, they found a small boat in which two-children were rowing about. It was a very small boat and can only carry the 2-children, or one grown person with it. How did the captain get himself and his 357 other soldiers across the river and leave the two-children finally in joint possession of their boat? And how many times need the boat pass from shore to shore?
You can get one grown person across as follows
The two children row across.
One child rows back.
The grown person rows across.
The other child rows back.
To generalise this to the captain and 357 soldiers
Just repeat the above procedure 358 times.
The boat passes shore to shore a total of
If the boys and their boat are initially on the opposite shore to the 358 men, then, for each man:
1. One boy rows across
2. One man rows across
3. The other boy rows across
4. Both boys row across
which is just a cyclic permutation of hexomino's answer. After
trips, all 358 men have now crossed, as required. Granted, the boys are now on opposite shores, but it wasn't required to return them both to one particular shore.