## 4x4x4 solver program

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### 4x4x4 solver program

Hi!
I'm creating a program to solve Rubik's Revenge.
I need to validate user inputs.
How can I determine that the scrambled Rubik's Revenge is solvable?
Thanks.
rdarida

Posts: 2
Joined: Sat Dec 08, 2012 8:30 am

### Re: 4x4x4 solver program

Check to make sure that:
-Each edge has TWO UNIQUE colours
-Each corner has THREE UNIQUE colours
-There are EXACTLY FOUR centers of each colour

Optional, this depends on your program:
-If there is an option for blank spaces, check to make sure ALL stickers are filled before proceeding
-If there is an option for more than 6 colours, check to make sure that there are EXACTLY SIX UNIQUE colours.
-If custom colour schemes are allowed, ask for opposite colour pairs first

(Yeah I know, a lot of caps emphasizing)
And these are probably obvious to you.

As for possibilities:
Since there is edge parity, you don't even need to care about flipped pairs.
Since it's a program, you need to care if they flip one edge, which isn't possible on a real cube because of its mechanism.

Since it is possible for corners to be twisted...
(This method is used in blindfold cubing)
-Pick two opposite colours (white/yellow)
-Pick two opposite faces (let's assume U and D for now)
-For each corner, count the number of clockwise twists to get the white or yellow sticker to the U or D face.
-If the number of twists is divisible by 3, you're fine.

Also, what language are you using? Just wondering :3
lol, here to help ^_~
Sharkretriver

Posts: 367
Joined: Thu Jul 14, 2011 10:11 pm
Location: Toronto, Canada

### Re: 4x4x4 solver program

Hi!
I want to implement in C, but first I will create it in Java (it's easier).
rdarida

Posts: 2
Joined: Sat Dec 08, 2012 8:30 am

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