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The Reve's Puzzle Lite

• App Store Info

Description

The classic "Reve's Puzzle" as described by Henry Dudeney in "The Canterbury Puzzles". The Reve, one of Chaucer's pilgrims, set up four stools and placed eight cheeses of differing sizes on one of the stools. He then challenged the other pilgrims to move the cheeses to another stool in the least number of moves possible. The cheeses must be moved one at a time and no cheese may be placed on a cheese that is smaller. After moving eight cheeses, the player has to move nine cheeses, and then ten, and so on until finally moving 21 cheeses. A pilgrim who is able to move 21 cheeses in the least number of moves will earn "a draught of the best that our good host can provide" from the Reve.

Please send us any comments or suggestions for additional changes to be considered for the Full Version.

Here's one comment that we received:

"Absolutely LOVE the animation. ... a brilliant implementation." David Mark

IN THE LITE VERSION the player can:

-- Move the cheeses as the Reve requires.
-- Take back an inadvertent move.
-- See the number of moves.
-- Start over again at any time.
-- Ask the Reve to move the cheeses.
-- Select from eight through 15 cheeses.

To move a piece of cheese, the player touches in a region near a stack of cheeses. The top piece on the stack moves to the player's finger. Then the player drops the cheese on another stack. If the move is not allowed, the piece returns to the stack where it started.

If the Reve is asked to demonstrate moving the cheeses, he will move them in the least number of moves possible but does not always move them the same way. The animation runs faster when there are more cheeses to be moved.

FULL VERSION: The Full Version has two modes, a practice mode and a puzzle mode. In practice mode, the player can practice moving from eight through 21 cheeses. The player can ask the Reve to demonstrate moving the cheeses but only in practice
mode.

In puzzle mode, the player has to move eight cheeses in the least number of moves possible, and then move nine, and then move ten, and so on until finally moving 21 cheeses in the least number of moves possible. At that point the Reve will hand the player a "draught of the best", and the player's name and the time that it took can be added to the honor roll of successful pilgrims.

The player can exit the puzzle at any time and resume from that point later.

It is fairly easy to move eight cheeses in the least number of moves, but it becomes more and more challenging as the number of cheeses increases. It takes at least 33 moves to move eight cheeses but takes at least 321 moves to move 21 cheeses. One mistake and you have to start all over.

The puzzle is similar to the Towers of Hanoi puzzle, but due to having four stools, it takes many fewer moves. At the same time, this puzzle is significantly more challenging. It is an unsolved problem in mathematics to find the minimum number of moves for all numbers of cheeses.