Programming Puzzles

An anonymous reader writes "Spotted over at the Economist: 'Sliding-block puzzles look easy, but they can be tricky to solve. The best known is the 15 Puzzle, which became hugely popular in the late 1870s. This involves square tiles labelled with the numbers 1 to 15, which must be arranged in the correct order inside a four-by-four frame.' While we've all tried these puzzles, the inventor of Quzzle set out to design the easiest looking - yet most difficult puzzle around and turned to CS to find it. While the original article touches on it, at the puzzle's site you'll find Jim Lewis, the inventor, wrote a program in Haskell, a functional programming language to find the best design."

Re:the 15-square puzzle

[Tablizer]

So if you have a friend with one of these puzzles, and you pry out two of the pieces and swap them, you will reverse the partiy of the game and he'll never be able to solve it.

My brother used to pull multiple Rubix Cubes apart and add extra color blocks to a side or two (making it unsolvable), and them give them to Rubix gurus to solve under the guise of needing help. It was interesting to watch them as their facial expression switched from a confident processing mode to confusion mode. We could take bets on how long it would take them to identify why it was not solvable. The good ol' Rubix days.

Re:I will help YOU get a JOB! (Programming puzzles

[Tablizer]

But if you really want to stump a slashdotter:

15. Go outside and meet girls.

Re:the 15-square puzzle

[AndyL]

I'll bet that the labels on most Rubix Cubes are easily removable.
If you swap the labels on two pieces it could make it unsolvable.

I'm looking at my Rubix Cube now and I'm noticing that a couple of the labels aren't on straight. Hmmmm....
Either this means that manufacturing standards are low enough that you probably wouldn't notice this type of hoaxing, or it means that someone has already done it to my Rubix cube and I still haven't noticed.

Re:FULL SOLUTION

[Zro Point Two]

hardest puzzle? bah...10 minutes and 37 moves total.
lets see if i can reproduce it here for people.
AD...1L...1L...2U...3U...6U...6U...3D...3 D...2R... 6U...6U...AR...4U...4U...5L...7L...8L...8U...7R... 7R...5D...8R...8R...AD...6D...6L...2L...3U...3U... AR...8L...8U...5U...7L...7L...AD

It's amazing what you can learn playing the 11th Hour :)