[Help Thread] 15 Puzzle Discussion

I'm not sure this really needs a home thread other than ben's sim thread, but okay. Here's some useful solving info.

The standard speed method for smaller puzzles (like 15 puzzle) is fringe. Basically the puzzle gets divided up like this:
Code:
A A A A
A B B B
A B C C
A B C
You would solve the A pieces first, then the B pieces, then the C pieces. Inside each fringe, you can either do the row part and then the column part, or the column part and then the row part, or both at once (if you see a way to do that). More efficient solvers use a lot of clever tricks to solve fringes, which you can learn from watching Ben's videos or optimal-fringe solves.

On smaller puzzles you can get away with moving pieces over one or two at a time, but on medium size puzzles (such as 99 puzzle) you will want to move trains of a few pieces up or left at once - that is, you might find 3-4 pieces from the first fringe's row, then put them in a column and move them all up in a single looping motion. I usually try to find all the pieces

On very big puzzles, fringe does work, but it becomes hard to tell the individual fringes apart, since there are so many colors. The best method seems to involve the grids color scheme, with a secondary scheme. Essentially the puzzle is grouped like this:
Code:
A A A B B B ...
A A A B B B ...
A A A B B B ...
C C C D D D ...
...
The squares A, B, C, D, ... can be any size but are commonly 1/4 or 1/5 of the main puzzle's size (so there will be 16 or 25 of them). Each of these squares has its own color, and then within a square, the secondary scheme lets you tell pieces apart so you can do a fringe or LBL solve. As for the actual method, you would bring all of the pieces of the first row of grids up to those locations, making a big rectangle; then, inside that row, you would bring all of the pieces of the first square left; then you would solve the first square. After that, you keep sorting squares until you finish the row, and then you do the entire thing again for the other rows of squares.

Also, people should learn mouse ;) Keyboard+macro > mouse > keyboard in terms of speed for big puzzles, but I and some others don't believe macros are fair comparison. You can do many moves per keystroke and get bursts of 100+ tps easily - it breaks the rule that an NxN puzzle should take (constant * N^3) inputs, and gives the grid method an artificial advantage due to working really nicely with spamming whole-row rotations (like L50 U R50 D ...).

Of course, ben and soup can provide more info ;)
 
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What's the bit of plastic sticking out of the 12 piece? Do all the pieces have that? That doesn't look like it's really doing much.
I'm pretty sure that's what keeps the pieces from falling out...it interlocks with grooves on the other pieces
 
Oh, of course.
But then... how did you get the pieces out to mod them? ;)

Yeah, there are grooves to keep the pieces from falling out when overturned. I basically pried out the 12 and 15 pieces with a screwdriver (didn't break them, luckily) and everything was super-easy to disassemble after that. For reassembly, I broke off a bit of the 12 piece's "torpedo" so that the the torpedo could actually fit through the florian mod holes.
 
It seems as though the 15 puzzle hasn't been very popular over the past few years but I recently got into it myself. I think it would a cool event to have competitions for but I don't know how big the audience is for it. If anyone would be interested in trying to hold a competition please reply so we can make that happen.
 
Hello. I am a beginner at 15 puzzle, I started 2 days ago. I average around 40-50 seconds and about 140-160 moves but I can see that most pros average around 60 to 70. I use LBL and I am trying to learn Fringe. I figured that if I can get my move count down, that my times will decrease exponentially, but I don't know how to go about doing so. Any help would be great! Thanks!
 
Efficiency is an important factor but so is look ahead. Think of the first 4 pieces as planning your cross out. I almost always start with 1,3,4 or 1,2,4 then squeeze the 2/3 in. Then I’ll place the 5 and move to 9,13. Under the right circumstance I might do the 1,9,13 or 1,5,13 first then squeeze the 5/9 in and move onto 2,3,4. I also might do LBL if it looks like the best continuation. I don’t know if sticking exclusively to fringe is really beneficial on 15 puzzle. I do use it exclusively on larger puzzles though. Hope this helps
 
Efficiency is an important factor but so is look ahead. Think of the first 4 pieces as planning your cross out. I almost always start with 1,3,4 or 1,2,4 then squeeze the 2/3 in. Then I’ll place the 5 and move to 9,13. Under the right circumstance I might do the 1,9,13 or 1,5,13 first then squeeze the 5/9 in and move onto 2,3,4. I also might do LBL if it looks like the best continuation. I don’t know if sticking exclusively to fringe is really beneficial on 15 puzzle. I do use it exclusively on larger puzzles though. Hope this helps
This does help, thank you!
 
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