Simulate a Rubik's cube

Question

A Rubik's cube has 6 colors: red, orange, yellow, white, blue, and green. Red and orange, yellow and white, and blue and green faces are on opposite sides.

Net of a solved Rubik's cube looks like this:

 Y
BRGO
 W

And the tiles look like this:

      Y Y Y
      Y Y Y
      Y Y Y
B B B R R R G G G O O O
B B B R R R G G G O O O
B B B R R R G G G O O O
      W W W
      W W W
      W W W

Challenge

Given rotations, reversed rotations, or double rotations output what a solved cube will transform to, as ASCII art or as an image (whitespaces aren't necessary, may or may not exist, trailing whitespaces are allowed.).

Input will be rotation (and optional modifier). Rotation notation goes like: U(p), L(eft), F(ront), R(ight), B(ack), D(own); 2 (double), ' or i (inverse).

All normal rotations will be 90° clockwise, inverse ones will be counterclockwise.

Explanation about clockwiseness: Imagine the cube as you're looking at the red face, and the yellow face is at the top. Then rotate the cube so that the face that the program will rotate will face you. This is the way clockwiseness will work. (Except back face, you will rotate the cube horizontally in that case.)

Input

Input will be a list of moves.

Output

An ASCII art that represents the cube or an image of the net of the cube.

Examples

Input: (empty)

Output:

      Y Y Y
      Y Y Y
      Y Y Y
B B B R R R G G G O O O
B B B R R R G G G O O O
B B B R R R G G G O O O
      W W W
      W W W
      W W W

Input: U (up)

Output:

      Y Y Y
      Y Y Y
      Y Y Y
R R R G G G O O O B B B
B B B R R R G G G O O O
B B B R R R G G G O O O
      W W W
      W W W
      W W W

Input: U' or Ui (inverse up)

Output:

      Y Y Y
      Y Y Y
      Y Y Y
O O O B B B R R R G G G
B B B R R R G G G O O O
B B B R R R G G G O O O
      W W W
      W W W
      W W W

Input: U2 (double up)

Output:

      Y Y Y
      Y Y Y
      Y Y Y
G G G O O O B B B R R R
B B B R R R G G G O O O
B B B R R R G G G O O O
      W W W
      W W W
      W W W

Input: L' (inversed left)

Output:

      R Y Y
      R Y Y
      R Y Y
B B B W R R G G G O O Y
B B B W R R G G G O O Y
B B B W R R G G G O O Y
      O W W
      O W W
      O W W

Input: R (right)

Output:

      Y Y R
      Y Y R
      Y Y R
B B B R R W G G G Y O O
B B B R R W G G G Y O O
B B B R R W G G G Y O O
      W W O
      W W O
      W W O

Input: U2 L' D (double up, inverse left, down)

Output:

      O Y Y
      R Y Y
      R Y Y
G B B W O O B B B R R Y
G B B W R R G G G O O Y
O O Y G B B W R R G G G
      R O O
      W W W
      W W W

Rules

• No loopholes allowed.
• This is code-golf, so shortest code in bytes solving the problem wins.

Answer 1

Ruby, 370 339 305 bytes

Latest edit: a few bytes saved by rearrangement of the plotting formulas and removal of unnecessary brackets. A massive saving by rewriting the generation of the cube - I never knew Ruby had a builtin for Cartesian Products!

->s{q=[-66,0,71].product [-87,0,89],[-79,0,82]
s.map{|c|m="LDBRUF".index c[0];e=m/3*2-1
c.sub(/[i']/,"33").chars{q.map{|j|j[m%=3]*e>0&&(j[m-2],j[m-1]=j[m-1]*e,-j[m-2]*e)}}}
t=[" "*12]*9*$/
q.map{|r|a,b,c=r.map{|i|i<=>0}
3.times{|i|r[i]!=0&&t[56+[a*3-a*c-d=b*13,a-d*3+d*c,3-d-c*3+c*a][i]]=r[i].abs.chr}}
t}

Anonymous function.

Accepts an array of strings, each representing one face turn (a single string with spaces between each face turn is an additional 6 bytes.)

Returns a 9x12 rectangular string.

Brief explanation

This is closely based on a concept from my answer to this question, which in turn was based on a similar concept by Jan Dvorak.

The first line generates a 27 element array, representing the 27 cubies. Each cubie is represented by a 3 dimensional vector in which the sign represents its current position and the magnitude of each coordinate represents the ascii code for the colour of the sticker.

Example move: for R, for each cubie check if the x coordinate is >0 and if so rotate 90 degrees by swapping the y and z coordinates and swapping the sign of one of them.

Take a 9x12 array of spaces and plot the cube into it. For each cubie and axis we check if the sticker exists (coordinate in that axis nonzero), and work out where it is to go. Then we take the coordinate and perform .abs.chr to change the number into the required character and plot it.

Ungolfed in test program (per 339 byte edit)

f=->s{

  q=(0..26).map{|i|                         #Build an array of 27 cubies
    [[-66,0,71][i%3],                       #x coordinate B.G
     [-87,0,89][i/3%3],                     #y coordinate Y.W
     [-79,0,82][i/9]]                       #z coordinate O.R
  }

  s.map{|c|                                 #For each move in the input array
    m="LDBRUF".index(c[0]);e=m/3*2-1        #m=face to move. e=-1 for LDB, +1 for RUF.
    c.sub(/[i']/,"33").chars{               #Substitute "i" and "'" for "33" so chars in string = clockwise 1/4 turns required. For each char...
      q.map{|j|j[m%=3]*e>0&&                #...and each cubie, m%3 tells the relevant axis. if coordinate*e>1 rotate the cubie 1/4 turn.
        (j[m-2],j[m-1]=j[m-1]*e,-j[m-2]*e)} #Swap other two axes and change sign of one. e performs sign change if necessary for LDB.
    }
  }

  t=[" "*12]*9*$/                           #Make an array of 9 strings of 12 spaces, then make a single string by joining them with newlines
  q.map{|r|                                 #For each cubie
    a,b,c=r.map{|i|i<=>0}                   #make a normalised (-1,0,1) copy of each coordinate.
    d=b*13                                  #13 chars per line, d will be useful for plotting to the correct line of the output.
    3.times{|i|                             #For each of the 3 coordinates of the cubie
      r[i]!=0&&                             #if zero, sticker doesn't exist (edges and centres have <3 stickers.) If not zero plot the sticker. 
      t[[56-d+a*3-a*c,                      #Calculate position on plot for x (L/R faces),
         56-d*3+d*c+a,                      #Calculate position on plot for y (D/U faces),
         59-d-c*3+c*a][i]]=                 #Calculate position on plot for z (B/F faces). Select the correct axis. 
      r[i].abs.chr                          #Convert the coordinate to a character and assign to the correct space on the output plot.
    }
  }
t}                                          #Return the output string.

puts f[gets.chomp.split]

Output

Checkerboard
U2 D2 F2 B2 L2 R2
   YWY
   WYW
   YWY
BGBRORGBGORO
GBGOROBGBROR
BGBRORGBGORO
   WYW
   YWY
   WYW

6-spot
U D' R L' F B' U D'
   RRR
   RYR
   RRR
WWWGGGYYYBBB
WBWGRGYGYBOB
WWWGGGYYYBBB
   OOO
   OWO
   OOO

Testcase
U2 L' D
   OYY
   RYY
   RYY
GBBWOOBBBRRY
GBBWRRGGGOOY
OOYGBBWRRGGG
   ROO
   WWW
   WWW

Answer 2

C, 1715 1709 1686 1336 1328 bytes

25 bytes saved thanks to @KevinCruijssen!

No answers so far, so I decided to put my own solution.

#define m(a,b,c,d)t[c][d]=r[a][b]; 
#define n(a)m(a,0,a,2)m(a,1,a,5)m(a,2,a,8)m(a,3,a,1)m(a,5,a,7)m(a,6,a,0)m(a,7,a,3)m(a,8,a,6)
#define y memcpy
typedef char R[6][9];R t;F(R r){y(t,r,54);n(0)m(4,6,1,0)m(4,7,1,3)m(4,8,1,6)m(1,0,5,0)m(1,3,5,1)m(1,6,5,2)m(5,0,3,2)m(5,1,3,5)m(5,2,3,8)m(3,2,4,6)m(3,5,4,7)m(3,8,4,8)y(r,t,54);}B(R r){y(t,r,54);n(2)m(1,2,4,0)m(1,5,4,1)m(1,8,4,2)m(3,0,5,6)m(3,3,5,7)m(3,6,5,8)m(4,0,3,6)m(4,1,3,3)m(4,2,3,0)m(5,6,1,8)m(5,7,1,5)m(5,8,1,2)y(r,t,54);}L(R r){y(t,r,54);n(3)m(0,0,5,0)m(0,3,5,3)m(0,6,5,6)m(2,2,4,6)m(2,5,4,3)m(2,8,4,0)m(4,0,0,0)m(4,3,0,3)m(4,6,0,6)m(5,0,2,8)m(5,3,2,5)m(5,6,2,2)y(r,t,54);}E(R r){y(t,r,54);n(1)m(0,2,4,2)m(0,5,4,5)m(0,8,4,8)m(5,2,0,2)m(5,5,0,5)m(5,8,0,8)m(4,2,2,6)m(4,5,2,3)m(4,8,2,0)m(2,0,5,8)m(2,3,5,5)m(2,6,5,2)y(r,t,54);}U(R r){y(t,r,54);n(4)m(0,0,3,0)m(0,1,3,1)m(0,2,3,2)m(1,0,0,0)m(1,1,0,1)m(1,2,0,2)m(2,0,1,0)m(2,1,1,1)m(2,2,1,2)m(3,0,2,0)m(3,1,2,1)m(3,2,2,2)y(r,t,54);}D(R r){y(t,r,54);n(5)m(0,6,1,6)m(0,7,1,7)m(0,8,1,8)m(1,6,2,6)m(1,7,2,7)m(1,8,2,8)m(2,6,3,6)m(2,7,3,7)m(2,8,3,8)m(3,6,0,6)m(3,7,0,7)m(3,8,0,8)y(r,t,54);}a,b,c,d,e,o,p,l;f(char*z,R s){char c[6]="RGOBYW";for(;b<7;b++)for(a=0;a<10;)s[b][a++]=c[b];for(l=strlen(z);l-->0;){d=*z++;if(d-32){e=*z++;if(*z++-32)*z++;o=e-50?e-39?1:3:2;for(p=0;p++<o;)d-70?d-66?d-76?d-82?d-85?D(s):U(s):E(s):L(s):B(s):F(s);}}}

Try it online!

Ungolfed old version:

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

typedef char Tile;
typedef Tile Face[10];
typedef Face Rubik[7];

void main_loop(Rubik);
void rubik_init(Rubik);
void rubik_print(Rubik);
void rotate(Rubik, char, char);
void print_tile(Rubik, int, int);

void F(Rubik);
void B(Rubik);
void L(Rubik);
void R(Rubik);
void U(Rubik);
void D(Rubik);

#define move(a, b, c, d) \
      temp[c][d] = rubik[a][b]

#define move_f(a) \
    move(a, 1, a, 3); \
    move(a, 2, a, 6); \
    move(a, 3, a, 9); \
    move(a, 4, a, 2); \
    move(a, 6, a, 8); \
    move(a, 7, a, 1); \
    move(a, 8, a, 4); \
    move(a, 9, a, 7)

void F(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(1);
    move(5, 7, 2, 1);
    move(5, 8, 2, 4);
    move(5, 9, 2, 7);
    move(2, 1, 6, 1);
    move(2, 4, 6, 2);
    move(2, 7, 6, 3);
    move(6, 1, 4, 3);
    move(6, 2, 4, 6);
    move(6, 3, 4, 9);
    move(4, 3, 5, 7);
    move(4, 6, 5, 8);
    move(4, 9, 5, 9);
    memcpy(rubik, temp, sizeof(Rubik));
}

void B(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(3);
    move(2, 3, 5, 1);
    move(2, 6, 5, 2);
    move(2, 9, 5, 3);
    move(4, 1, 6, 7);
    move(4, 4, 6, 8);
    move(4, 7, 6, 9);
    move(5, 1, 4, 7);
    move(5, 2, 4, 4);
    move(5, 3, 4, 1);
    move(6, 7, 2, 9);
    move(6, 8, 2, 6);
    move(6, 9, 2, 3);
    memcpy(rubik, temp, sizeof(Rubik));
}

void L(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(4);
    move(1, 1, 6, 1);
    move(1, 4, 6, 4);
    move(1, 7, 6, 7);
    move(3, 3, 5, 7);
    move(3, 6, 5, 4);
    move(3, 9, 5, 1);
    move(5, 1, 1, 1);
    move(5, 4, 1, 4);
    move(5, 7, 1, 7);
    move(6, 1, 3, 9);
    move(6, 4, 3, 6);
    move(6, 7, 3, 3);
    memcpy(rubik, temp, sizeof(Rubik));
}

void R(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(2);
    move(1, 3, 5, 3);
    move(1, 6, 5, 6);
    move(1, 9, 5, 9);
    move(6, 3, 1, 3);
    move(6, 6, 1, 6);
    move(6, 9, 1, 9);
    move(5, 3, 3, 7);
    move(5, 6, 3, 4);
    move(5, 9, 3, 1);
    move(3, 1, 6, 9);
    move(3, 4, 6, 6);
    move(3, 7, 6, 3);
    memcpy(rubik, temp, sizeof(Rubik));
}

void U(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(5);
    move(1, 1, 4, 1);
    move(1, 2, 4, 2);
    move(1, 3, 4, 3);
    move(2, 1, 1, 1);
    move(2, 2, 1, 2);
    move(2, 3, 1, 3);
    move(3, 1, 2, 1);
    move(3, 2, 2, 2);
    move(3, 3, 2, 3);
    move(4, 1, 3, 1);
    move(4, 2, 3, 2);
    move(4, 3, 3, 3);
    memcpy(rubik, temp, sizeof(Rubik));
}

void D(Rubik rubik) {
    Rubik temp;
    memcpy(temp, rubik, sizeof(Rubik));
    move_f(6);
    move(1, 7, 2, 7);
    move(1, 8, 2, 8);
    move(1, 9, 2, 9);
    move(2, 7, 3, 7);
    move(2, 8, 3, 8);
    move(2, 9, 3, 9);
    move(3, 7, 4, 7);
    move(3, 8, 4, 8);
    move(3, 9, 4, 9);
    move(4, 7, 1, 7);
    move(4, 8, 1, 8);
    move(4, 9, 1, 9);
    memcpy(rubik, temp, sizeof(Rubik));
}

int main(int argc, char *argv[]) {
    Rubik rubik;
    rubik_init(rubik);
    main_loop(rubik);
    return 0;
}

void main_loop(Rubik rubik) {
    char a, b;
    for (;;) {
        a=toupper(getchar());
        if (a == 'Q') break;
        if (a != 10) {
            b=toupper(getchar());
            if (b != 10) getchar();
            rotate(rubik, a, b);
        }
        rubik_print(rubik);
    }
}

void rubik_init(Rubik rubik) {
    int i,n;
    char c[7] = " RGOBYW";

    for (n=1; n<=7; n++)
        for (i=1; i<=10; i++)
            rubik[n][i] = c[n];
}

void rotate(Rubik rubik, char a, char b){
    int i = b == '2' ? 2 : b == '\'' || b == toupper('i') ? 3 : 1;
    int j;
    for (j=0; j<i; j++)
        if (a == 'F') F(rubik);
        else if (a == 'B') B(rubik);
        else if (a == 'L') L(rubik);
        else if (a == 'R') R(rubik);
        else if (a == 'U') U(rubik);
        else if (a == 'D') D(rubik);
        else;
}

void rubik_print(Rubik rubik) {
    int i,j,k;

    for (i=1; i<=9; i++)
        if (i%3==0) {
            print_tile(rubik,5,i);
            printf("\n");
        }
        else if (i%3==1) {
            printf("    ");
            print_tile(rubik,5,i);
        }
        else
            print_tile(rubik,5,i);

    printf("\n");

    for (k=1; k<=3; k++) {
        for (i=3; i<=6; i++) {
            for (j=k*3-2; j<=k*3; j++)
                print_tile(rubik, i%4+1, j);
            printf(" ");
        }
        printf("\n");
    }

    printf("\n");

    for (i=1; i<=9; i++)
        if (i%3==0) {
            print_tile(rubik, 6, i);
            printf("\n");
        }
        else if (i%3==1) {
            printf("    ");
            print_tile(rubik, 6, i);
        }
        else
            print_tile(rubik, 6, i);

}

void print_tile(Rubik rubik, int a, int b) {
    switch (rubik[a][b]) {
      case 'R':
        printf("R");
        break;
      case 'O':
        printf("O");
        break;
      case 'B':
        printf("B");
        break;
      case 'G':
        printf("G");
        break;
      case 'Y':
        printf("Y");
        break;
      case 'W':
        printf("W");
        break;
      default:
        exit(1);
    }
}

Answer 3

Javascript (ES5), 1615 bytes

function m(a){b=[];b[0]=a[6];b[2]=a[0];b[8]=a[2];b[6]=a[8];b[1]=a[3];b[5]=a[1];b[7]=a[5];b[3]=a[7];b[4]=a[4];return b}function q(a,b){c=[];c[0]=b[0];c[1]=b[1];c[2]=a[2];c[3]=b[3];c[4]=b[4];c[5]=a[5];c[6]=b[6];c[7]=b[7];c[8]=a[8];return c}function r(a){var b=[];b[0]=m(a[0]);b[1]=q(a[2],a[1]);b[4]=q(a[1],a[4]);b[3]=q(a[4],a[3]);b[2]=q(a[3],a[2]);b[5]=a[5];return b}function x(a){var b=[];b[0]=m(a[0]);b[1]=a[2];b[2]=a[3];b[3]=a[4];b[4]=a[1];b[5]=m(m(m(a[5])));return b}function y(a){var b=[];b[0]=a[4];b[1]=m(a[1]);b[2]=a[0];b[3]=m(m(m(a[3])));b[4]=a[5];b[5]=a[2];return b}function s(a){a=a.replace(/F2/,"F F");a=a.replace(/R2/,"R R");a=a.replace(/U2/,"U U");a=a.replace(/D2/,"D D");a=a.replace(/B2/,"B B");a=a.replace(/L2/,"L L");a=a.replace(/F'/,"F F F");a=a.replace(/R'/,"R R R");a=a.replace(/U'/,"U U U");a=a.replace(/D'/,"D D D");a=a.replace(/B'/,"B B B");a=a.replace(/L'/,"L L L");a=a.replace(/F/,"y y y R y");a=a.replace(/L/,"y y R y y");a=a.replace(/U/,"x y R y y y x x x");a=a.replace(/B/,"y R y y y");a=a.replace(/D/,"x y y y R y x x x");a=a.split(" ");for(b=["RRRRRRRRR".split(""),"WWWWWWWWW".split(""),"GGGGGGGGG".split(""),"YYYYYYYYY".split(""),"BBBBBBBBB".split(""),"OOOOOOOOO".split("")],c=0;c<a.length;++c)"x"==a[c]?b=x(b):"y"==a[c]?b=y(b):"R"==a[c]&&(b=r(b));return p(b)}function p(a){for(var b="",c=0;3>c;++c)b+="\n   "+a[1][3*c+0]+a[1][3*c+1]+a[1][3*c+2];for(c=0;3>c;++c)b+="\n"+a[5][3*c+0]+a[5][3*c+1]+a[5][3*c+2]+a[2][3*c+0]+a[2][3*c+1]+a[2][3*c+2]+a[0][3*c+0]+a[0][3*c+1]+a[0][3*c+2]+a[4][3*c+0]+a[4][3*c+1]+a[4][3*c+2];for(c=0;3>c;++c)b+="\n   "+a[3][3*c+0]+a[3][3*c+1]+a[3][3*c+2];return b}

Ungolfed:

function m(fac){ //Turn a face
    //0 1 2
    //3 4 5
    //6 7 8

    var fac2=[];
    fac2[0]=fac[6];
    fac2[2]=fac[0];
    fac2[8]=fac[2];
    fac2[6]=fac[8];

    fac2[1]=fac[3];
    fac2[5]=fac[1];
    fac2[7]=fac[5];
    fac2[3]=fac[7];

    fac2[4]=fac[4];

    return fac2;
}

function q(face1,face3){ //Swap right third of two faces
    var face2=[];
    face2[0]=face3[0];
    face2[1]=face3[1];
    face2[2]=face1[2];
    face2[3]=face3[3];
    face2[4]=face3[4];
    face2[5]=face1[5];
    face2[6]=face3[6];
    face2[7]=face3[7];
    face2[8]=face1[8];
    return face2;
}

function r(state){ //Apply a R move
    var state2=[];
    state2[0]=m(state[0]);
    //Swap right set of Front, Up, Back, Down (2,1,4,3);

    state2[1]=q(state[2],state[1]);
    state2[4]=q(state[1],state[4]);
    state2[3]=q(state[4],state[3]);
    state2[2]=q(state[3],state[2]);
    state2[5]=state[5];
    return state2;
}

function x(staten){ //Apply a x move
    var state2=[];
    state2[0]=m(staten[0]);
    state2[1]=staten[2];
    state2[2]=staten[3];
    state2[3]=staten[4];
    state2[4]=staten[1];
    state2[5]=m(m(m(staten[5])));
    return state2;
}

function y(state){ //Apply a y move
    var state2=[];
    state2[0]=state[4];
    state2[1]=m(state[1]);
    state2[2]=state[0];
    state2[3]=m(m(m(state[3])));
    state2[4]=state[5];
    state2[5]=state[2];
    return state2;
}

function s(algo){ //Solve a cube, representing every move with x, y and R
    algo=algo.replace(/F2/,"F F");
    algo=algo.replace(/R2/,"R R");
    algo=algo.replace(/U2/,"U U");
    algo=algo.replace(/D2/,"D D");
    algo=algo.replace(/B2/,"B B");
    algo=algo.replace(/L2/,"L L");

    algo=algo.replace(/F'/,"F F F");
    algo=algo.replace(/R'/,"R R R");
    algo=algo.replace(/U'/,"U U U");
    algo=algo.replace(/D'/,"D D D");
    algo=algo.replace(/B'/,"B B B");
    algo=algo.replace(/L'/,"L L L");

    algo=algo.replace(/F/,"y y y R y");
    algo=algo.replace(/L/,"y y R y y");
    algo=algo.replace(/U/,"x y R y y y x x x");
    algo=algo.replace(/B/,"y R y y y");
    algo=algo.replace(/D/,"x y y y R y x x x");

    algo=algo.split(" ");

    var cstate=[["R","R","R","R","R","R","R","R","R"],["W","W","W","W","W","W","W","W","W"],["G","G","G","G","G","G","G","G","G"],["Y","Y","Y","Y","Y","Y","Y","Y","Y"],["B","B","B","B","B","B","B","B","B"],["O","O","O","O","O","O","O","O","O"]];

    for(var i=0;i<algo.length;++i){
        if(algo[i]=="x"){
            cstate=x(cstate);
        }else if(algo[i]=="y"){
            cstate=y(cstate);
        }else if(algo[i]=="R"){
            cstate=r(cstate);
        }
    }

    return p(cstate);
}

function p(cstate){ //Print
    var out="";
    var leftspace="\n   ";
    for(var i=0;i<3;++i){
        out+=leftspace+cstate[1][3*i+0]+cstate[1][3*i+1]+cstate[1][3*i+2]
    }
    for(var i=0;i<3;++i){
        out+="\n"+cstate[5][3*i+0]+cstate[5][3*i+1]+cstate[5][3*i+2]+cstate[2][3*i+0]+cstate[2][3*i+1]+cstate[2][3*i+2]+cstate[0][3*i+0]+cstate[0][3*i+1]+cstate[0][3*i+2]+cstate[4][3*i+0]+cstate[4][3*i+1]+cstate[4][3*i+2]
    }
    for(var i=0;i<3;++i){
        out+=leftspace+cstate[3][3*i+0]+cstate[3][3*i+1]+cstate[3][3*i+2]
    }
    return out;
}

This was a very difficult challenge.

Explanation

Take the example call s("R U' F").

The program can only execute x, y and R moves.

U' is equal to U U U, so replace that.

F is equal to y y y R y, so replace that.

R U' F' is therefore equal to R U U U y y y R y, which the program can run.

cstate is defined with a solved cube. A cube is represented by an array containing 6 arrays containing the 9 stickers. The first array is for R, second for U, third for F, D, B, last array is for L. When an y needs to be executed, the program swaps the four arrays of the front, left, back and right face. For an x, it swaps front, down, back and top. Every rotation also rotates the other faces, that were not swapped. A R move rotates the right face and swaps the right part of the front, up, back, down face.

This could be modified to be able to solve problems with all types of moves, by defining them with x, y and R.

Answer 4

Python 3,  610 563 533  526 bytes

-7 bytes thanks to my colleague rhsmits (really nice d,*c form & removal of redundant parentheses)

This is a full program.

import re
d,*c=[f*9for f in' YBRGOW']
r=lambda f:[f[int(v)]for v in'630741852']
U=lambda c:[r(c[0])]+[c[j%4+1][:3]+c[j][3:]for j in(1,2,3,4)]+[c[5]]
y=lambda c:[r(c[0])]+c[2:5]+[c[1],r(r(r(c[5])))]
z=lambda c:[c[2],r(r(r(c[1]))),c[5],r(c[3]),c[0][::-1],c[4][::-1]]
exec("c="+"(c);c=".join("".join("zzzUz U zzUzz yyyzUzzzy zUzzz yzUzzzyyy".split()[ord(t)%11%7]*(ord(n or'a')%6)for t,n in re.findall("([B-U])(['2i]?)",input())))+"(c)")
k=' '.join
for q in[d,c[0]],c[1:5],[d,c[5]]:
 for w in 0,3,6:print(k(k(f[w:w+3])for f in q))

Superflip and all tests are available at ideone or Try it online!

The program:

• creates the six faces YBRGOW of stickers.
• creates a function, r, which only rotates the stickers on a face, clockwise a quarter-turn
• creates a function, U, which rotates the U face clockwise a quarter-turn by applying r and rotating the stickers on the top-band of LFRB clockwise a quarter-turn
• creates a function, y, which performs r on the U and D faces and slices LFRB
  - this performs a rotation of the whole cube in the y axis (which runs through U and D)
  - the rotation is clockwise if looking from above
• creates a function z, which performs a rotation of the whole cube in the z axis clockwise a quarter turn looking at R (the axis runs through R and L) - this time because the way the faces are oriented in our net (same as given in the OP) we have to flip the B and U faces over (they switch from the horizontal to vertical parts of the net and vice-versa)
• Performs a regex on the input, input(), (the moves to be performed) matching a character from BUDLRF (actually B-U) possibly followed by a character 'i2
• Performs a mapping from the 'i2 to the number of clockwise turns (the ordinals of these mod 6 does the job, with a dummy a to yield 1 when none is present)
• Performs a lookup to map each of these single clockwise turn instructions to a setup of calls to y and z, a quarter-turn of U (which will now be the face instructed), and then the calls to inverse the sequence of the setup performed. Taking the ordinal of the face character modulo by 11 then by 7 maps B:0 U:1 D:2 L:3 F:4 R:5, allowing a simple indexing into a string of the function name sequences split by spaces.
• executes the string to actually perform the manoeuvre
• creates a dummy face d to shorten the printing
• prints the result by stepping through the rows in the net and the faces in the row (including a dummy face to the left of each of U and D

Here is the superflip:

D:\Python Scripts>python rubiksAscii.py
U R2 F B R B2 R U2 L B2 R U' D' R2 F R' L B2 U2 F2
      Y O Y
      B Y G
      Y R Y
B Y B R Y R G Y G O Y O
O B R B R G R G O G O B
B W B R W R G W G O W O
      W R W
      B W G
      W O W

Answer 5

Python 760 750 649 Bytes

shamelessly stole the idea of using only 3 rotations from @Paul Schmitz :D

new version:

from numpy import*
c=kron([[32,89,32,32],[66,82,71,79],[32,87,32,32]],ones([3,3])).astype(int)
def x():t=copy(c);c[:3,3:6],c[3:6,3:6],c[6:,3:6],c[3:6,9:],c[3:6,:3],c[3:6,6:9]=t[3:6,3:6],t[6:,3:6],rot90(t[3:6,9:],2),rot90(t[:3,3:6],2),rot90(t[3:6,:3]),rot90(t[3:6,6:9],3)
def y():c[3:6],c[:3,3:6],c[6:,3:6]=roll(c[3:6],3,1),rot90(c[:3,3:6]),rot90(c[6:,3:6],3)
def F():c[2:7,2:7]=rot90(c[2:7,2:7],3)
s=raw_input()
for p in"':i,Fi:FFF,F2:FF,Bi:BBB,B2:BB,Ri:RRR,R2:RR,Li:LLL,L2:LL,Ui:UUU,U2:UU,Di:DDD,D2:DD,B:xxFxx,R:yyyFy,L:yFyyy,U:xxxFx,D:xFxxx".split(','):s=s.replace(*p.split(':'))
for S in s:eval(S+'()')
for r in c:print(''.join(chr(x)for x in r))

I mostly just did lots of numpy list slicing and used its built in rotate and roll functions. Input is handled by calling the functions directly with eval()

from numpy import*
l=[0];c=kron([[32,89,32,32],[66,82,71,79],[32,87,32,32]],ones([3,3])).astype(int)
def i():l[0]();l[0]()
def d():l[0]()
def U():c[:3,3:6]=rot90(c[:3,3:6],3);c[3]=roll(c[3],9);l[0]=U
def D():c[6:,3:6]=rot90(c[6:,3:6],3);c[5]=roll(c[5],3);l[0]=D
def F():c[2:7,2:7]=rot90(c[2:7,2:7],3);l[0]=F
def B():c[3:6,9:]=rot90(c[3:6,9:],3);t=copy(c);c[:,:9],c[1:-1,1:8]=rot90(t[:,:9]),t[1:-1,1:8];l[0]=B
def R():c[3:6,6:9]=rot90(c[3:6,6:9],3);t=copy(c);c[:6,5],c[3:6,9],c[6:,5]=t[3:,5],t[2::-1,5],t[5:2:-1,9];l[0]=R
def L():c[3:6,:3]=rot90(c[3:6,:3],3);t=copy(c);c[3:,3],c[3:6,-1],c[:3,3]=t[:6,3],t[:5:-1,3],t[5:2:-1,-1];l[0]=L
for s in raw_input().replace("'",'i').replace('2','d').replace(' ',''):eval(s+'()')
for r in c:print(''.join(chr(x)for x in r))

ungolfed..

import numpy as np
last = [0] #store last move to repeat for inverse or double
           #list is shorter syntax than global var

cube = np.array([
[' ',' ',' ','Y','Y','Y',' ',' ',' ',' ',' ',' '],
[' ',' ',' ','Y','Y','Y',' ',' ',' ',' ',' ',' '],
[' ',' ',' ','Y','Y','Y',' ',' ',' ',' ',' ',' '],
['B','B','B','R','R','R','G','G','G','O','O','O'],
['B','B','B','R','R','R','G','G','G','O','O','O'],
['B','B','B','R','R','R','G','G','G','O','O','O'],
[' ',' ',' ','W','W','W',' ',' ',' ',' ',' ',' '],
[' ',' ',' ','W','W','W',' ',' ',' ',' ',' ',' '],
[' ',' ',' ','W','W','W',' ',' ',' ',' ',' ',' ']
]) #ascii ascii codes in golfed version

def i(): #triple move (inverse)
    last[0]()
    last[0]()

def d(): #double move
    last[0]()

def U(): #clockwise upface (yellow)
    cube[:3,3:6] = np.rot90(cube[:3,3:6],3)
    cube[3] = np.roll(cube[3],9)
    last[0] = U

def D(): #clockwise downface (white)
    cube[6:,3:6] = np.rot90(cube[6:,3:6],3)
    cube[5] = np.roll(cube[5],3)
    last[0] = D

def F(): #clockwise frontface (red)
    cube[2:7,2:7] = np.rot90(cube[2:7,2:7],3)
    last[0] = F

def B(): #clockwise backface (orange)
    cube[3:6,9:] = np.rot90(cube[3:6,9:],3)
    tempCube = np.copy(cube)
    cube[:,:9],cube[1:-1,1:8] = np.rot90(tempCube[:,:9]),tempCube[1:-1,1:8]
    last[0] = B

def R(): #clockwise rightface (green)
    cube[3:6,6:9] = np.rot90(cube[3:6,6:9],3)
    tempCube = np.copy(cube)
    cube[:6,5],cube[3:6,9],cube[6:,5] = tempCube[3:,5],tempCube[2::-1,5],tempCube[5:2:-1,9]
    last[0] = R

def L(): #clockwise leftface (blue)
    cube[3:6,:3] = np.rot90(cube[3:6,:3],3)
    tempCube = np.copy(cube)
    cube[3:,3],cube[3:6,-1],cube[:3,3] = tempCube[:6,3],tempCube[:5:-1,3],tempCube[5:2:-1,-1]
    last[0] = L


for character in raw_input('type a move sequence: ').replace("'",'i').replace('2','d').replace(' ',''):
    eval(character+'()')

print("-"*12)

for row in cube:
    print(''.join(character for character in row)) #uses ascii codes in golfed version

test input:

>>> runfile('C:~/rubiks cube.py', wdir='C:~/python/golf')
U2 L' D
   OYY      
   RYY      
   RYY      
GBBWOOBBBRRY
GBBWRRGGGOOY
OOYGBBWRRGGG
   ROO      
   WWW      
   WWW 

Comments or suggestions are greatly appreciated :)

Answer 6

C, 839 bytes

#include <stdio.h>
#define b(c) c,c+1,c+2,c+15,c+28,c+27,c+26,c+13
char a[]="   YYY      \n   YYY      \n   YYY      \nBBBRRRGGGOOO\nBBBRRRGGGOOO\nBBBRRRGGGOOO\n   WWW      \n   WWW      \n   WWW      \n",k;int d[][8]={b(3),b(39),b(42),b(45),b(48),b(81)},e[][12]={50,49,48,47,46,45,44,43,42,41,40,39,3,16,29,42,55,68,81,94,107,76,63,50,29,30,31,45,58,71,83,82,81,67,54,41,109,96,83,70,57,44,31,18,5,48,61,74,39,52,65,107,108,109,73,60,47,5,4,3,65,66,67,68,69,70,71,72,73,74,75,76},i,*j,r,p,q,s;f(int*g,int h){i=h<0?-1:1;for(j=g;j!=g+h;j+=i){k=a[j[3*h]];for(r=3;r--;)a[j[r*h+h]]=a[j[r*h]];a[*j]=k;}}l(int g,int m){f(d[g+m]-m,m?-2:2);f(e[g+m]-m,m?-3:3);}void n(char*o){while(*o){*o-'U'||(p=0);*o-'L'||(p=1);*o-'F'||(p=2);*o-'R'||(p=3);*o-'B'||(p=4);*o-'D'||(p=5);s=*++o=='\''||*o=='i';q=*o=='2';(s||q)&&o++;l(p,s);q&&l(p,0);}printf("%s",a);}

As this is not a full program (function with input from a string argument and output to the console), you need to call it like this:

int main() {
//  n("U2D2R2L2F2B2");    //checker cube
    n("UDiRL'FBiUD'");    //spotted cube
}

Use only one call at a time as the function uses and modifies global variables.

Ungolfed:

#include <stdio.h>

char cube[] = "   YYY      \n"
              "   YYY      \n"
              "   YYY      \n"
              "BBBRRRGGGOOO\n"
              "BBBRRRGGGOOO\n"
              "BBBRRRGGGOOO\n"
              "   WWW      \n"
              "   WWW      \n"
              "   WWW      \n";

#define faceMove(offset) offset,offset+1,offset+2,offset+15,offset+28,offset+27,offset+26,offset+13
int faceMoves[6][8] = {
    faceMove(3),    //Up
    faceMove(39),   //Left
    faceMove(42),   //Front
    faceMove(45),   //Right
    faceMove(48),   //Back
    faceMove(81)    //Down
}, lineMoves[6][12] = {
    50,49,48,47,46,45,44,43,42,41,40,39,    //Up
    3,16,29,42,55,68,81,94,107,76,63,50,    //Left
    29,30,31,45,58,71,83,82,81,67,54,41,    //Front
    109,96,83,70,57,44,31,18,5,48,61,74,    //Right
    39,52,65,107,108,109,73,60,47,5,4,3,    //Back
    65,66,67,68,69,70,71,72,73,74,75,76 //Down
};

int rotate(int*move,int rotation){
    int sign=rotation<0?-1:1;
    for(int*submove=move;submove!=move+rotation;submove+=sign){
        char takeout=cube[submove[3*rotation]];
        for(int j=3;j--;)cube[submove[j*rotation+rotation]]=cube[submove[j*rotation]];
        cube[*submove]=takeout;
    }
}

int move(int move,int inverted){
    rotate(faceMoves[move+inverted]-inverted,inverted?-2:2);
    rotate(lineMoves[move+inverted]-inverted,inverted?-3:3);
}

void performMoves(char*instructions){
    while(*instructions){
        int moveIndex;
        *instructions-'U'||(moveIndex=0);
        *instructions-'L'||(moveIndex=1);
        *instructions-'F'||(moveIndex=2);
        *instructions-'R'||(moveIndex=3);
        *instructions-'B'||(moveIndex=4);
        *instructions-'D'||(moveIndex=5);
        int inverted=*++instructions=='\''||*instructions=='i', twice=*instructions=='2';
        (inverted||twice)&&instructions++;
        move(moveIndex,inverted);
        twice&&move(moveIndex,0);
    }
    printf("%s",cube);
}

int main() {
//  performMoves("U2D2R2L2F2B2");    //checker cube
    performMoves("UDiRL'FBiUD'");    //spotted cube
}

As you can see, the main idea is to use a fully data-driven approach: The different rotations are expressed as lists of indices that have to be permuted. The permutation code can thus be very short and generic.

Answer 7

Cubically, 2 bytes

¶■

Try it online!

Explanation:

¶   read a line from stdin, evaluate
 ■  print the cube to stdout

---

If extraneous output is allowed, this is an alternative. 1 byte:

¶

Try it online!

Cubically automatically dumps its memory cube to STDERR when the program ends. However, it also prints the notepad beforehand.

Answer 8

JavaScript (ES6), 820

A porting of the buggy answer by @Paul Schmitz. It's still not completely golfed, but it has the added value that it works.

The main problem in the original answer is that a single function Q is not enough for all the movements involved in a rotation. I had to add 2 other functions O and N. All of them are just called in the right rotation function R.

(a,M=a=>[a[6],a[3],a[0],a[7],a[4],a[1],a[8],a[5],a[2]],Q=(a,b)=>[b[0],b[1],a[2],b[3],b[4],a[5],b[6],b[7],a[8]],N=(a,b)=>[b[0],b[1],a[6],b[3],b[4],a[3],b[6],b[7],a[0]],O=(a,b)=>[b[8],a[1],a[2],b[5],a[4],a[5],b[2],a[7],a[8]],R=a=>[M(a[0]),Q(a[2],a[1]),Q(a[3],a[2]),N(a[4],a[3]),O(a[4],a[1]),a[5]],X=a=>[M(a[0]),a[2],a[3],M(M(a[4])),M(M(a[1])),M(M(M(a[5])))],Y=a=>[a[4],M(a[1]),a[0],M(M(M(a[3]))),a[5],a[2]],F=c=>Array(9).fill(c[0]),r='replace',b=[F`G`,F`Y`,F`R`,F`W`,F`O`,F`B`],J=(p,l)=>p.join``[r](/.../g,l))=>(a[r](/(.)2/g,"$1$1")[r](/(.)['i]/g,"$1$1$1")[r](/F/g,"yyyRy")[r](/L/g,"yyRyy")[r](/B/g,"yRyyy")[r](/U/g,"xyRyyyxxx")[r](/D/g,"xyyyRyxxx")[r](/\w/g,c=>b=(c<'a'?R:c<'y'?X:Y)(b)),o=J(b[1],`
   $&`),J(b[5],(c,p)=>o+=`
`+c+b[2].join``.substr(p,3)+b[0].join``.substr(p,3)+b[4].join``.substr(p,3)),o+J(b[3],`
   $&`))

More readable maybe

( 
  a, 
  // local variables as default parameters
  r='replace',
  F=c=>Array(9).fill(c[0]), // function to fill a 3x3 square
  b=[F`G`,F`Y`,F`R`,F`W`,F`O`,F`B`], // cube status
  // aux functions to perform basic moves
  M=a=>[a[6],a[3],a[0],a[7],a[4],a[1],a[8],a[5],a[2]],
  Q=(a,b)=>[b[0],b[1],a[2],b[3],b[4],a[5],b[6],b[7],a[8]],
  N=(a,b)=>[b[0],b[1],a[6],b[3],b[4],a[3],b[6],b[7],a[0]],
  O=(a,b)=>[b[8],a[1],a[2],b[5],a[4],a[5],b[2],a[7],a[8]],
  // R : right side rotation
  R=a=>[M(a[0]),Q(a[2],a[1]),Q(a[3],a[2]),N(a[4],a[3]),O(a[4],a[1]),a[5]],
  // X,Y: to put other sides in place of right side
  X=a=>[M(a[0]),a[2],a[3],M(M(a[4])),M(M(a[1])),M(M(M(a[5])))],
  Y=a=>[a[4],M(a[1]),a[0],M(M(M(a[3]))),a[5],a[2]],
  // aux function for output
  J=(p,l)=>p.join``[r](/.../g,l),
) => (
  // convert common moves to basic moves
  a[r](/(.)2/g,"$1$1")[r](/(.)['i]/g,"$1$1$1")[r](/F/g,"yyyRy")[r](/L/g,"yyRyy")[r](/B/g,"yRyyy")[r](/U/g,"xyRyyyxxx")[r](/D/g,"xyyyRyxxx")
  // then execute each
  [r](/\w/g,c=>b=c<'a'?R(b):c<'y'?X(b):Y(b)),
  // built output in o
  o=J(b[1],'\n   $&'),
  J(b[5],(c,p)=>o+='\n'+c+b[2].join``.substr(p,3)+b[0].join``.substr(p,3)+b[4].join``.substr(p,3)),
  o+J(b[3],'\n   $&') // returned output
)

S=
(a,M=a=>[a[6],a[3],a[0],a[7],a[4],a[1],a[8],a[5],a[2]],Q=(a,b)=>[b[0],b[1],a[2],b[3],b[4],a[5],b[6],b[7],a[8]],N=(a,b)=>[b[0],b[1],a[6],b[3],b[4],a[3],b[6],b[7],a[0]],O=(a,b)=>[b[8],a[1],a[2],b[5],a[4],a[5],b[2],a[7],a[8]],R=a=>[M(a[0]),Q(a[2],a[1]),Q(a[3],a[2]),N(a[4],a[3]),O(a[4],a[1]),a[5]],X=a=>[M(a[0]),a[2],a[3],M(M(a[4])),M(M(a[1])),M(M(M(a[5])))],Y=a=>[a[4],M(a[1]),a[0],M(M(M(a[3]))),a[5],a[2]],F=c=>Array(9).fill(c[0]),r='replace',b=[F`G`,F`Y`,F`R`,F`W`,F`O`,F`B`],J=(p,l)=>p.join``[r](/.../g,l))=>(a[r](/(.)2/g,"$1$1")[r](/(.)['i]/g,"$1$1$1")[r](/F/g,"yyyRy")[r](/L/g,"yyRyy")[r](/B/g,"yRyyy")[r](/U/g,"xyRyyyxxx")[r](/D/g,"xyyyRyxxx")[r](/\w/g,c=>b=(c<'a'?R:c<'y'?X:Y)(b)),o=J(b[1],`
   $&`),J(b[5],(c,p)=>o+=`
`+c+b[2].join``.substr(p,3)+b[0].join``.substr(p,3)+b[4].join``.substr(p,3)),o+J(b[3],`
   $&`))

function update() { O.textContent=S(I.value) }

update()

<input id=I value='U2 Li D' oninput='update()'><pre id=O></pre>