Five pirates who need a strict majority
Five pirates, ranked 5 (most senior) down to 1, must divide 100 gold coins. The most senior pirate proposes a division and everyone, including the proposer, votes. In the classic puzzle the proposal passes with at least half the votes. In this version it must win strictly more than half. If it fails, the proposer is thrown overboard and the next most senior pirate proposes.
Pirates are perfectly rational and, in order of priority: they want to survive; then they want as much gold as possible; and when indifferent they prefer to see someone thrown overboard.
What does pirate 5 propose, and how much does he keep?
Show a hint
Work backwards from two pirates. With a strict majority required, what happens to a proposer who has only one other voter?
Your answer
Solving needs a free account
Answers, streaks and solutions unlock when you are signed in. Reading the question and the hint stays free.
Discussion
💡 Discussion rules
- No full solutions here. Hints and approaches only.
- Complexity, edge cases and intuition are the point.
- Interview experiences are welcome. Respect your NDAs.
Loading discussion…
Learn the concepts
The theory behind this question.