Fifteen Soldiers and Two Boys
Fifteen soldiers and two boys stand on one bank of a river. The only boat holds either one soldier or up to two boys (never a soldier together with a boy, and never two soldiers), and needs at least one person aboard to move. Every trip, in either direction, counts as one crossing. What is the minimum number of crossings needed to get all seventeen people to the other bank?
Related problems & prerequisites
Worth solving first
- The Twelve-Litre Cask 4.0/10
- The Bridge at Night 4.0/10
Source: Classic river-crossing puzzle (soldiers and boys) in wide circulation; no traceable original source. Statement written for AxiomIQ.