Water Jug PuzzleFree, no sign-up

None of the jugs have markings, so the only amounts you know are empty and full. Fill a jug from the tap, empty it out, or pour it into another jug (until the other jug is full or this one is empty). Combine these to get exactly the target amount in any one jug.

Fill and Empty under each jug are one move each. To pour, tap the jug to pour from, then tap the jug to pour into (tap the same jug again to change your mind). Actions that change nothing, such as filling a full jug or pouring from an empty one, don't count as moves. Undo (or the Z key) takes back the last move, and undone moves don't count (only the moves you keep are submitted).

It changes at midnight Japan time (UTC+9) and is the same for everyone. The jug sizes and target change every day. The computer works out the fewest moves and only picks puzzles whose best solution is 4 to 6 moves on Easy, 8 to 10 on Normal and 7 to 12 on Hard (where every puzzle needs all three jugs for the best solution), so there are no unsolvable puzzles and none that take three moves or fewer. A puzzle doesn't come back until every puzzle of that level has been used (60+ days). You'll be told when you solve it in the fewest moves.

By moves, fewest first; ties go to the shorter time. You only need a nickname, and you can submit up to 30 times a day. The server replays your moves to check them.

It's a classic pouring puzzle, known in Japan since the Edo period as “oil-splitting arithmetic”. Many people know it from Die Hard with a Vengeance, where the heroes must measure 4 gallons with a 3-gallon and a 5-gallon jug.