Skewb Random State Scrambler

skewb.py

center = [0]*360;
corner = [0]*8748;
centermv = [[0 for col in range(4)] for row in range(360)];
cornermv = [[0 for col in range(4)] for row in range(8748)];

def cycle3(arr, i1, i2, i3):
    c = arr[i1];
    arr[i1] = arr[i2];
    arr[i2] = arr[i3];
    arr[i3] = c;

def getctmv(p, m):
    ps = [0, 0, 0, 0, 0, 1];
    s = 0;
    for i in range(3, -1, -1):
        p, ps[i] = divmod(p, 6-i);
        s = s + ps[i];
        for j in range(i+1, 6):
            if (ps[j] >= ps[i]):
                ps[j] += 1;
    if (s % 2 == 1):
        temp = ps[5];
        ps[5] = ps[4];
        ps[4] = temp;
    if (m==0):#L
        cycle3(ps, 0, 5, 1);
    elif (m==1):#R
        cycle3(ps, 0, 2, 4);
    elif (m==2):#D
        cycle3(ps, 1, 3, 2);
    elif (m==3):#B
        cycle3(ps, 3, 5, 4);
    idx = 0;
    for i in range(0, 4):
        idx *= (6-i);
        for j in range(i+1, 6):
            if (ps[i] > ps[j]):
                idx += 1;
    return idx;    

    
def getcnmv(p, m):
    ps = [0] * 8;#twists
    for i in range(0, 7):
        p, ps[i] = divmod(p, 3);
    ps[7] = (30 - ps[4] - ps[5] - ps[6]) % 3;
#    fc = p;#the position of one free corners is enough
    fcmv = [[1, 2, 0, 3], [2, 1, 3, 0], [3, 0, 2, 1], [0, 3, 1, 2]];
    p = fcmv[m][p];
    ps[m] = (ps[m] + 1) % 3;
    if (m==0):
        ps[5], ps[6], ps[4] = ps[4]+2, ps[5]+2, ps[6]+2;#TODO
    elif (m==1):
        ps[6], ps[7], ps[4] = ps[4]+2, ps[6]+2, ps[7]+2;#TODO
    elif (m==2):
        ps[7], ps[4], ps[5] = ps[4]+2, ps[5]+2, ps[7]+2;#TODO
    elif (m==3):
        ps[7], ps[5], ps[6] = ps[5]+2, ps[6]+2, ps[7]+2;#TODO
    for i in range(6, -1, -1):
        p = p * 3 + (ps[i] % 3);
    return p;

def calcperm():
    for p in range(0, 360):
        center[p]=-1;
        for m in range(0, 4):
            centermv[p][m] = getctmv(p,m);
    for p in range(0, 8748):
        corner[p]=-1;
        for m in range(0, 4):
            cornermv[p][m] = getcnmv(p,m);
            
#    glb = [-1] * (3149280);
#    glb[0] = 0;
#    for l in range(0, 11):
#        n=0;
#        for p in range(0, 3149280):
#            if (glb[p]==l):
#                for m in range(0, 4):
#                    q=p;
#                    for c in range(0, 2):
#                    	a, b = divmod(q, 360);
#                        q = cornermv[a][m] * 360 + centermv[b][m];
#                        if (glb[q]==-1):
#                            glb[q]=l+1;
#                            n+=1;
#        print n;

    center[0]=0;
    for l in range(0, 5):
        n=0;
        for p in range(0, 360):
            if (center[p]==l):
                for m in range(0, 4):
                    q=p;
                    for c in range(0, 2):
                        q = centermv[q][m];
                        if (center[q]==-1):
                            center[q]=l+1;
                            n+=1; 
#        print n;                   
    corner[0]=0;
    for l in range(0, 7):
        n=0;
        for p in range(0, 8748):
            if (corner[p]==l):
                for m in range(0, 4):
                    q=p;
                    for c in range(0, 2):
                        q = cornermv[q][m];
                        if (corner[q]==-1):
                            corner[q]=l+1;
                            n+=1;
#        print n;            
         

def search(sol, ct, cn, l, lm):
#    searches for solution, from position q|t, in l moves exactly. last move was lm, current depth=d
    if (l==0):
        if (ct==0 and cn==0):
            return True;
    else:
        if (center[ct]>l or corner[cn]>l):
            return False;
        for m in range(0, 4):
            if (m!=lm):
                p=ct;
                s=cn;
                for a in range(0, 2):
                    p = centermv[p][m];
                    s = cornermv[s][m];
                    sol.append('LRDB'[m]+' \''[a]);
                    if (search(sol, p, s, l-1, m)):
                        return 1;
                    sol.pop();
    return 0;
    
def gets():
    sol = [];
    import random;
    cn=random.randint(0, 8747);#3^7*4
    ct=random.randint(0, 359);#6!/2
    for l in range(0, 100):
        if(search(sol, ct, cn, l,-1)):
            break;
    return ' '.join(sol);
    
calcperm();