# ZZF2L 'Openslotting' Algorithms



## Cride5 (Jul 30, 2010)

When solving ZZF2L I find myself inserting C+E pairs into 'open' slots almost as often as closed ones. Although it can improve efficiency, the main reason I do it is for lookahead. Where an initial 1x2x2 belongs in a front slot, I normally place it into the back to fill up the hidden edge positions (BL and BR).

Although I've been doing this for quite a while, I've never actually looked at the best algs for solving into an open slot. While some of the cases are best solved by closing the slot and executing the normal alg, many cases can be more efficiently solved by an alg optimised for this situation.

All cases are presented below for completeness, however some of them can probably be ignored. Some are based on just closing the slot, while others can be easily worked out through intuition.


Basic Cases


(U) L' U R U' L . . (5f)
(U) R U2 R' U' R . . (5f)


(U) R' U L U' R2 U L' . . (7f)
(U) R2 D R' U2 R D' R' . . (7f)
(U') R U2 R' U' R U R' U' R . . (9f)


R2 U2 R2 U' R2 U' R' . . (7f)


R U R' U' R U' R' U' R . . (9f)
R U2 R' U R U R' U' R . . (9f)
R B2 U L U' L' B2 . . (7f)


(U') R U2 R' U R U' R' U R . . (9f)
(U) R' U2 R2 U R2 U R2 . . (7f)


(U') R U' R' U R U' R' U R . . (9f)
R U R' U2 R U2 R' U R . . (9f)
R B2 U2 R B2 R' U2 B2 . . (8f)



Corner Trapped


R U2 R' U R . . (5f)


R U' R' U' R . . (5f)


R U L' U R' U' L R . . (8f)
L R U' R' U L' U R . . (8f)
R U R' U' R U' R' U R . . (9f)



Edge Trapped


R U R' U' R . .(5f)


R U' R' U R . . (5f)


R U R' U R U' R' U' R . . (9f)
(U') L' U2 L F2 R' F2 R2 . . (7f)
(U') L' U2 R U2 R' U2 L R . . (8f)



Both Trapped


R' U2 R' U R U' R U2 R2 . . (9f)
R2 U2 R U' R U R' U2 R' . . (9f)
F2 U' F2 R' D R' D' R' . . (8f)
R' D' R' D R' B2 U' B2 . . (8f)


R U' R U2 R2 U' R2 U' R' . . (9f)
R' U' R2 U' R2 U2 R U' R . . (9f)


R U R2 U2 R U R' U R2 . . (9f)
R2 U R' U R U2 R2 U R . . (9f)



Connected Cases


R U' R' U' L' U R U' L . . (9f)
R U R' U2 R U' R' U' R . . (9f)
F R B R' F' R B' . . (7f)
F' R B R' F R B' . . (7f)


(U') R U R' U' R U R' U' R . . (9f)
R' U' R2 U' R2 U2 R2 . . (7f)


R U' R' U2 R U' R' U R . . (9f)
(U) R' U' R U' R' U2 R2 . . (7f)


(U) R' U2 R U R' U R2 . . (7f)


R B2 L U L' U' B2 (7f)
(U) L' U2 L U L' U L R . . (8f)
R U R' U' R U R' U2 R . . (9f)
(U2) R U R' U2 R U R' U' R . . (9f)


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## koreancuber (Jul 30, 2010)

great, I'll have to look into this sometime


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## Cride5 (Jul 30, 2010)

Cheers.

Cases added to the ZZ Tutorial.


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## StachuK1992 (Jul 30, 2010)

I saw this thread last night, and was seriously sad when I saw now that it didn't have more posts!

This is great stuff (apart from the first 3, which are *really* intuitive )

Already they've been helping me....and distracting me from other puzzles. heehee

Great job,
statue


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## irontwig (Jul 30, 2010)

Cride5 said:


> Cheers.
> 
> Cases added to the ZZ Tutorial.



Time for more than one page, perhaps?


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## Cride5 (Jul 30, 2010)

Stachuk1992 said:


> Already they've been helping me....and distracting me from other puzzles. heehee
> 
> Great job,
> statue


Good to hear it. Cheers 




irontwig said:


> Cride5 said:
> 
> 
> > Cheers.
> ...



Hmm, yes it would probably be a good idea. I think it has reached the point where the benefits of using one page are outweighed by huge amount of data downloaded on each request.


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## koreancuber (Jul 31, 2010)

added to the ZZ/ZB home thread


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## Matt S (Jul 31, 2010)

Great work as usual Cride.

For almost all of the cases, the intuitive solution is the best, which is nice although a bit boring. I'm glad I'm not being enticed into trying short but ugly algs, since using F and B doesn't appear to save more than two turns in any case.

On a side note, I love to leave an open slot when the opposite side is still completely unsolved, because you have total freedom to make the pair.


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## Cride5 (Jul 31, 2010)

Yup, having a slot open when you have a whole side free is an ideal situation, because the pair can be built quite efficiently, and then inserted very efficiently. 

During my solves I don't like to enforce a specific block order, because it may be difficult to find specific pieces, but I find that the blockbuild is usually more efficient if I can finish a whole side before moving onto the next 1x2x2. The best situation is to be able to build the whole LH side first, building the blocks with R/U moves, then moving onto the RH side. Completing a whole side first means that 'algs' are only really necessary for the final C+E pair.


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