Towers of Hanoi
- If there is only one disk move it directly from the source peg to the target peg. Otherwise:
- Ignore the bottom disk of the tower on the source peg, and solve the Towers of Hanoi problem from the source peg to the spare peg, using the target peg as a spare. The spare peg now has a tower of n-1 disks on it, and the source peg has one disk (the biggest) on it.
- Move the single disk from the source peg to the target peg.
- Solve the Towers of Hanoi problem from the spare peg to the target peg using the source peg as a spare.
open/close all folders
- Perplex City borrows the Hindu legend for the card Tower of Cubes, though their temple only has 36 cubes to work with, and completing the puzzle will end all sorrow and grief in the universe.
- If you move one disc per second, this would take 2,179 years, 29 days, 7 hours, 32 minutes and 15 seconds. Not as long as the other example.
- "Bright Eyes", the ape in Rise of the Planet of the Apes, is seen flying through this puzzle, though it was a four disc variant and she was tested on it repeatedly.
- In Eric Frank Russell's story "Now Inhale", the protagonist is sentenced to death on an alien world. Traditionally, the condemned plays a game with the warder, and when it ends (win or lose) he is executed. To stretch the game out until rescuers arrive, our hero chooses the Towers of Hanoi, referencing the above legend. When the aliens discover they've been duped, they change the rules so that offworld games are not allowed.
- In the Doctor Who serial "The Celestial Toymaker" (now a lost story except for the final episode, but available in full on audio), the Doctor is challenged to solve a 10-disc version of the Towers of Hanoi, known as The Trilogic Game. The Doctor realises that the Toymaker's world will vanish once he makes the last move, so he finishes it inside the TARDIS.
- On Survivor Thailand (U.S. season 5), a version of this puzzle was an immunity challenge.
- The MMORPG EverQuest has a quest where you have to play Towers of Hanoi, although they don't call it that.
- In Star Wars: The Old Republic, the Fabricator boss in the Karraga's Palace Operation requires some members of the party to solve this type of puzzle to arm the cannon that lowers the boss' defenses.
- One of the activities in Math Blaster Pre-Algebra is a variation on the Towers of Hanoi where barrels in the basement must be stacked to solve a math problem. Rather than varying sizes of barrels, it uses varying numbers on the barrels which must add up to the number on the platform. There are three places to put the barrels and four barrels. There are two platforms which may or may not have different numbers.
- BioWare seems to like this puzzle:
- It shows up in Star Wars: Knights of the Old Republic, Jade Empire, and Mass Effect 1note .
- In Dragon Age: Origins, it is instead mocked by a gravestone in Haven reading "T.O. Hanoi. Unloved, unmourned."
- But used again (repeatedly) in Star Wars: The Old Republic, where the puzzle is part of the activation of a plasma vent used in the penultimate Boss Fight of Karagga's Palace.
- One of the game machines seen in the arcade included in the Mass Effect 3 Citadel DLC is "Towers of Hanoi." Shepard's reaction: "I don't think so."
- Dragon Age: Inquisition's Descent DLC features the "Builder's Towers" puzzle as an optional sidequest, but still lampshades its infamy by having your character call it insane.
- A side quest in Black & White has you doing this to move a temple further up the shore of a lake so it doesn't get flooded out during high tide. The inclusion of "classic" puzzles caused some reviewers to wonder whether Hanoi Towers and garbage collecting is really what gods do.
- The stairway puzzle in Ultima VIII is a version with stair steps.
- This is the last puzzle in The Legend of Kyrandia: Hand of Fate.
- To finish Zork Zero, the player has to go through this twice (at least). Even nastier, you're not allowed to save while in the room, and if you put a big disc onto a smaller one, it crushes the smaller one, making the game Unwinnable. Hope you saved often!
- Subverted in the Interactive Fiction game The Magic Toyshop, where you're challenged to solve the puzzle in only six moves. The solution is to glue two of the disks together (using two moves), leaving you with a two-disk tower and four moves.
- Professor Layton and the Diabolical Box, which uses pancakes in place of discs and plates instead of pegs.
- A side mission to explore an abandoned mansion in Space Rangers 2 has this as one of the puzzles.
- The third screen in The Island of Dr. Brain has this puzzle with 4, 5, or 7 discs, depending on the difficulty. Expect to be there a while on Expert difficulty making 127 moves.
- The Tire Tower puzzle in The Secret Island of Dr. Quandary. 3 tires as B. Ginner, 4 as O.D. Nary, 5 as D. Feecult, and each with a limit on the moves you can use before your time is up and Quandary kicks you out of the junkyard.
- Appears in its four-tier form in Mystery Of Mortlake Mansion.
- All the time in the Nancy Drew series. There's one in The Haunting of Castle Malloy that springs to mind first.
- A common test (amongst others) for diagnosing schizophrenia. Schizoid-type disorders are notable for an inability to plan means-to-a-goal actions and so are impaired at the puzzle.