# 20 turns suffice for 3x3x3!



## cmhardw (Aug 18, 2009)

Just kidding! This hasn't been proven yet. You've just been

Surprise Challenged by Chris Hardwick!

There's only one Golden Rule:

*Surprise Challenge Golden Rule)* Do the challenge listed below *within the next week*.

Clarification of the #1 rule: If you clicked this thread, then you must do the challenge as described.

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Ok, here's the challenge!

3x3x3 Forced Turns Fewest Moves Challenge

You have a maximum of one week to complete the following challenge. The challenge is to solve the following scramble in the fewest number of turns (HTM) as possible. However, every 10th turn of your solution must be *F'* - these are the "forced" turns. This rule applies whether you solve the scramble or the inverse scramble. If you do choose to solve the inverse scramble, then every 10th turn of the solution you build must be an *F'*. This will result in every 10th turn of the solution to the scrambling algorithm, starting from the end of the solution, being an *F*. The *F*, or front layer, is fixed throughout the entire solve and is defined as the face that was on the front of the cube upon execution of the scrambling algorithm.

After each "forced" turn you may not turn the *F* layer again until the 2nd move after the forced turn. This means that you cannot simply undo the forced turn with an *F* immediately after. In fact, you can't turn the *F* layer at all immediately after the forced turn - but it is allowed again the 2nd turn after each forced turn. You must find your solution without the aid of any computer solver, use just your brain!

Remember, this surprise challenge is a bit different in that you may take up to a full week before posting your solution. Let's keep this interesting and submit all solutions before August 31. Try to surprise others with a link to this thread!

The scramble is listed below, good luck! Remember, you must do the challenge *within the next week*.

3x3x3 Forced Turns Fewest Moves Challenge: R' F R' D' U' F2 B U2 F2 L' F R2 U' B2 L R2 F' B2 D2 U' L2 U L2 B F2

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*Fun Variation #1*

*Additional Rules and Clarifications for a more enjoyable (and difficult) challenge:*

Clarification 1) If cube rotations are used at any point during the solve, then the front face is still defined as the face that was on the front of the cube when you applied the scrambling algorithm. This face must be turned once counterclockwise every 10th turn (whether you use cube rotations or not)

Clarification 2) You may not use any computer *solvers*, but you can use computer aids to see if your solution works. Just don't use ACube to find useful 8 or 9 move transformations ;-)

*Additional Rule #1)* Ok now the additional rule that makes this more fun. Every 9th and every 11th turns may not be turns of the *F* layer. Remember, by *F* layer I mean that layer that was the front face as you applied the scrambling algorithm. For example, say this is the green face. If you rotate the cube during your solve, then every 9th turn and every 11th turn, may *not* be turns of the green layer. In addition, the "forced" moves from the original challenge still apply. This means that every 10th turn must be to turn the green layer counterclockwise one turn in my example.
--/EDIT--

*Fun Variation #2*

For those who have completed the above challenges, or for those who want to try the most difficult version of the challenge of all, then try the following fun variation.

All of the rules mentioned below apply for Fun Variation #2:

1) The front face must be turned once counterclockwise every 10th turn of your solve. The front face is fixed throughout the duration of the entire solve, and is defined as the face that was on the front of the cube when you applied the scrambling algorithm.

2) If you do choose to solve the inverse scramble, then every 10th turn of the solution must follow rule #1 above. This will result in every 10th turn of the solution to the scrambling algorithm, starting from the end of the solution, being an *F* turn.

3) Every 9th and every 11th turn of your scramble may *not* be a turn of the front layer. The front layer is fixed through the duration of the solve and is defined as the layer that was on the front of the cube when you applied the scrambling algorithm.

3) You may not do more than 2 turns of parallel layers in a row. For example the sequence B F B' F' is not allowed as this counts as 4 turns of parallel layers in a row.

4) Cube rotations may be used, but you *must* turn the *original* front layer every 10th turn. Also, all of the above rules apply still. Cube rotations do not count as one of the turns of your solution.

5) The solution is measured in HTM, and thus slice turns are not allowed. The slice turn E must be written as either U D' or U D' y' and counts either way as 2 turns.

6) You may *not* turn the same layer twice in succession at any point during the solve. For example doing R R2 or R' R is not allowed at any point during your solve.
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Once again, Good Luck Everyone!
Chris


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## kickinwing2112 (Aug 18, 2009)

you get me every time time, the worst was on the 2-7 blind relay link


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## coolmission (Aug 18, 2009)

Hats off to Chris, he gets me every time as well. And usually at work


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## Sa967St (Aug 18, 2009)

no fair!! Maarten linked me to this thread D:

there's no way I'm doing this, I'll take a DNF.


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## coolmission (Aug 18, 2009)

Sa967St said:


> no fair!! Maarten linked me to this thread D:
> 
> there's no way I'm doing this, I'll take a DNF.



Cmon Sarah, you have a whole week to do it 

We should really implement a warning page; every time you are about to view a thread by Chris, there should be a huge warning banner asking us for confirmation at least 10 or 15 times.


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## trying-to-speedcube... (Aug 18, 2009)

Big props to anyone who can find an insertion in his solve 



coolmission said:


> Sa967St said:
> 
> 
> > no fair!! Maarten linked me to this thread D:
> ...


Chris is a moderator himself; I don't think he's going to let that happen 

EDIT: Found a 19 move F2L minus one corner, but I can't find a nice continuation. (Would end up sup-70!!) So my solution is:

2x2x2 Block: L U L2 U2 R F B R B' F'
2x2x3 Block: U L D L' U' 
2xcross+useless moves: x2 y' F2 U2 L F L'
3rd pair+useless moves: F U F' U' F U F' U' L L'
4th pair+useless moves: F L F L' F L F' L' L L'
OLL+useless moves: R U L' U L U2 R' F L L'
Start of PLL+useless moves: R F2 R' F' R F2 L' U L L'
End of PLL: R' F' L

63 moves.


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## coolmission (Aug 18, 2009)

Well, you can always use Greasemonkey.

A script a day keeps those challenges away!


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## trying-to-speedcube... (Aug 18, 2009)

coolmission said:


> A script a day keeps those challenges away!


Signatured.


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## Lucas Garron (Aug 18, 2009)

1) Are cube rotations allowed?
2) May we use a computer?
3) Your description is not clear: I presume we're not allowed to perform an F-move on turn 9?

EDIT: 75 linear first attempt. Will try to type up.
EDIT 2: 76, actually:
U L2 B' D' B' U2 L F L' F R F2 R' F' R F R' F' U' F U F' U F U' F' L' F2 L2 F L' F' L' U L' U' L2 F2 D F D' F' D F D' F' D F D' F R' F L' F R F' L F2 R' F R L' F L F' L2 U' F' U F L U L' U' L2 F
Terrible end, so I will try to improve it. Based on this.


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## trying-to-speedcube... (Aug 18, 2009)

1) Yes, but the F face moves with it.
2) Yes, but no solving programs may be used.
3) It doesn't say so, so you can 

Lucas, every 10th move has to be F', not F


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## Inf3rn0 (Aug 18, 2009)

Aw you got me. But im glad you did cause this sounds fun as!!!!!! Ill begin giving it a go after school tomorrow, my goal is to get sub 100 lol. Man im keen, so looking foward to starting this.


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## LNZ (Aug 18, 2009)

When computers powerful enough to run through all 4.32E19 states of the 3x3cube become available, I'm sure we'll know gods algorithm at last for the 3x3 cube. We already know it for the 1x1x1 (0) and 2x2x2 (11) cubes. The upper bound for the 3x3x3 least moves is 22 and the lowest is 20.


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## StachuK1992 (Aug 18, 2009)

LNZ. That, somewhat ironically, is completely off-topic here, despite the thread title.

on-topic:
Grr...I'll do this later, for sure!


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## cmhardw (Aug 18, 2009)

Lucas Garron said:


> 1) Are cube rotations allowed?
> 2) May we use a computer?
> 3) Your description is not clear: I presume we're not allowed to perform an F-move on turn 9?



Good questions Lucas.

1) Yes they are, but the face that was originally your front face when you scrambled (for example, green) must be turned once counterclockwise every 10th turn of your solve.

2) I meant that you must find the solution without the aid of computer solvers. So using tools to help see if your solution works is ok, just don't plug anything into ACube to find any useful 8 or 9 move transformations ;-)

3) Actually, I didn't think of that, and that kind of does ruin the whole challenge if you just do F every 9th turn. Thanks for pointing that out, I'll fix the original post. I'll say that F turns are banned one turn before, and one turn after the 10th turns, so as to not allow for any cancellations. Plus it makes it harder to do the challenge ;-)

Chris

P.S. This challenge is posted in puzzle theory since I wanted to post more of a head scratcher/difficult challenge this time.

--EDIT--
I changed the original post to be what I intended the challenge to be, sorry if it was not clear the first time. I thought I caught every loophole ;-)


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## piemaster (Aug 18, 2009)

ARghh! I have to remember not to view ANY threads by chris that has something amazing as a thread title.


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## trying-to-speedcube... (Aug 18, 2009)

But Chris, do I have to change my solution now? I posted it before you said it's illegal...


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## cmhardw (Aug 18, 2009)

trying-to-speedcube... said:


> But Chris, do I have to change my solution now? I posted it before you said it's illegal...



No, you can continue as the original challenge.

I posted the --edit-- or addendum as a possible variation. You can continue the work you've already done if you would rather not do the variation.

Chris


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## JL58 (Aug 18, 2009)

Wouldn't a BF'B'F sequence every 10 turns defeat the purpose?


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## Lucas Garron (Aug 18, 2009)

cmhardw said:


> 1) Yes they are, but the face that was originally your front face when you scrambled (for example, green) must be turned once counterclockwise every 10th turn of your solve.


That was only half of it.
4) Are cube rotations allowed as spacefiller moves? Or do they not count as moves?

Also:
5) Are slice turns allowed, and how are they handled?

I'm not trying to annoy you, I'm just trying not to break your intention of the challenge.


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## trying-to-speedcube... (Aug 18, 2009)

They aren't in real FMC, so neither are they here I think.


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## Lucas Garron (Aug 18, 2009)

trying-to-speedcube... said:


> They aren't in real FMC, so neither are they here I think.


Cube rotations or slice moves? Also, could you stop trying to answer for Chris?

65 Moves

Very natural solve:

x y' L F2 D' R' D' L2' y' R U R' U
L U2 L' U' L U L' U' y' R' U
R U' R U R' y U' R' U2 R2 U
R' U' R' U' R U R' U' R d
L' d' R d L U' r' U' r d
y2 R' U2 R' U' y R' F' R2 U' R' U
R' F R U' F


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## fanwuq (Aug 18, 2009)

What happens if my 9th move was a F2?

BD'F2U'R2)D2F'D2F2

Or, Can the 10th move be a F2?

Are we allowed to do something like R R' in the middle of the solution?

I got 25 moves with F'L2 premoves for F2L+EO and can't go further until my questions are clarified.

RU'R2L2U2D2B2)U'BF')L2B'L)U2L'U'LU2LF')L'UFU2F2)


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## trying-to-speedcube... (Aug 18, 2009)

Lucas Garron said:


> trying-to-speedcube... said:
> 
> 
> > They aren't in real FMC, so neither are they here I think.
> ...


I'm not answering to a question you edited into your post after mine. So cube rotations. 

I will not reply to your questions anymore.


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## Feanaro (Aug 18, 2009)

D2 R' L2 B2 D' R' U' R U' F'
U' F2 U F' U R U' R' U' F'
L F L' R' U2 R U' F U F'
U L' U L B' U B U R' F'
U F U' R' F R F' U R F'
U' F R F' U' F U F R' F'
F' U F U2

64 Move solution, and my first Fewest Moves contest ever


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## Lucas Garron (Aug 18, 2009)

Finally! Got a 33-move solution.

Was trying really hard to make it under 40 and avoid the constraint, but then I found a much better ending.

My trick:


Spoiler



Take that, Chris!
(spacing)
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(spacing)


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## TMOY (Aug 18, 2009)

Here is a nice solution I found; You can easily check that all the highlighted moves involve the face which started as F.

u2 l D l' x2 y' U2 R U' R F2 *R'* U R f2 (13) corners + 2 edges, up to 2 moves
x2 z' F E2 F' D2 L' (6) insert another edge and finish corners
*D'* R' E2 R B2 F' E' F (10) 3 more edges
y' *D'* U2 L' E L2 E' L2 E (= U *D'* y') L D R2 U2 D' (16) last 6 edges
Total: 45 HTM


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## qqwref (Aug 19, 2009)

OK, I'm going to try this.

[Around an hour later] I have found a solution! It is 66 moves, not so great, but I think it's not all that bad considering the constraint.

```
[COLOR="white"]D2 R' L2 B2 D  R  U2 F  U  [B]F'[/B]
R' D2 F' U  F  D' L' D  L  [B]F'[/B]
L' R  U' R' F2 R  U' R' U  [B]F'[/B]
U' F2 U2 F' U' F  U' F  U  [B]F'[/B]
U' F' U  F' U' L2 U2 F  D  [B]F'[/B]
U2 F  D' F' L2 F  L2 F  D  [B]F'[/B]
U2 F  D' F' U2 L2[/COLOR]
```


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## xXdaveXsuperstarXx (Aug 19, 2009)

I'm a rebel. Worse then any Rebel Roux or those nasty hybrids of Fridrich-Roux people. I *Refuse the challenge. * *Instant I click submit button I get sniped*..... No, seriously I don't feel like it.


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## cmhardw (Aug 19, 2009)

The spirit of the challenge is to find a solution while minimizing the damage caused by the forced turns, or possibly even being clever enough to utilize the forced turns to aid you in your solving. I will try to write a more clear variation to the puzzle that basically does this.

Obviously I was not clear with the first post, and I don't want to make people angry who have already started working on solutions, so any changes will only be implemented as a new variation that can be attempted.

Of course you can avoid the forced turns with stuff like B F' B' F, but try to follow the spirit of the event for a more fun solve ;-)

Chris

P.S. Wonderful 33 move solution Lucas, I would never have thought to do that! I totally got cube rolled! Nice one!


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## mrCage (Aug 21, 2009)

Hi Chris. I know why you specified every *TENth (or less)* move to be a F/F' move. Otherwise there are "trivial" long solutions ...

Per


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