Various
The 15 puzzle is a sliding puzzle.
The wolf, goat and cabbage problem is a river crossing puzzle.
Natural sorting orders strings in a more human-friendly manner than a purely alphabetical (or ascii) sort order.
Roman numerals are a numeral system that originated in ancient Rome.
Knight’s Tour - a sequence of moves of a knight on a chessboard such that the knight visits every square exactly once.
Eight Queens Puzzle - placing chess queens so that no two queens challenge each other.
FizzBuzz - a simple experiment in test-driven development.