Loyd's Dilemma

This is one of the OLD POTM problems

Long version of the problem.

Information about the winner and the solution

Back to the list of problems.

Short Problem Description

Deadline was April, 1995.

When I was a kid, I had a little toy with 15 number tiles in a 4x4 frame arranged so that I could slide the numbers around and put them in order. If memory serves (and it frequently doesn't), the puzzle was attributed to Sam Loyd and was called Loyd's Fifteen puzzle. Hence, we have the seeds for the next Programmer Of The Month (POTM):


* * * L O Y D ' S D I L E M M A * * *

A B C D E F G H I J K L M N O P Q R S T U V W X +

Imagine 24 tiles, with the upper case letters A through X. These tiles are in a 5 by 5 frame such that they cannot slide outside the boundary of the frame. The empty spot in the square is marked with a "+" for our convenience. The figure above represents perfection. Your goal will be to achieve perfection when starting with chaos.

At your disposal are five moves, each of which describes the movement of a tile into the empty spot. There are the obvious four: LEFT, RIGHT, UP, and DOWN plus a new wrinkle: TRANSPORT (which moves the center tile to the empty spot).

Well - that's about it for the short form problem statement. I'll give you a messed up square, and your program prints out a series of moves that cause it to become perfection! Shortest sequence of moves achieving perfection will win - tiebreakers are in the details!

If you want to compete - you'll need these details. Simply send mail to enter@potm.ffast.att.com and I'll ship you the details and put you on the weekly status mailing list for this problem. (A reply to this mail should do the trick!)

Hope you'll consider having some fun and entering this one!!! Deadline will be 11:59 PM on Sunday April 30, 1995.

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