def set_d_edges(self, idx):
slice_edge = [Ed.DR, Ed.DF, Ed.DL, Ed.DB]
other_edge = [Ed.FR, Ed.FL, Ed.BL, Ed.BR, Ed.UR, Ed.UF, Ed.UL, Ed.UB]
b = idx % 24 # Permutation
a = idx // 24 # Location
for e in Ed:
self.ep[e] = -1 # Invalidate all edge positions
j = 1 # generate permutation from index b
while j < 4:
k = b % (j + 1)
b //= j + 1
while k > 0:
rotate_right(slice_edge, 0, j)
k -= 1
j += 1
x = 4 # set slice edges
for j in Ed:
if a - c_nk(11 - j, x) >= 0:
self.ep[j] = slice_edge[4 - x]
a -= c_nk(11 - j, x)
x -= 1
x = 0 # set the remaining edges UR..DB
for j in Ed:
if self.ep[j] == -1:
self.ep[j] = other_edge[x]
x += 1
for j in range(4):
rotate_left(self.ep, 0, 11)
def get_slice(self):
"""Location of the UD-slice edges FR,FL,BL and BR ignoring their permutation."""
a = x = 0
# Compute the index a < (12 choose 4)
for j in range(Ed.BR, Ed.UR - 1, -1):
if Ed.FR <= self.ep[j] <= Ed.BR:
a += c_nk(11 - j, x + 1)
x += 1
return a
def set_slice(self, idx):
slice_edge = list(range(Ed.FR, Ed.BR + 1))
other_edge = [Ed.UR, Ed.UF, Ed.UL, Ed.UB, Ed.DR, Ed.DF, Ed.DL, Ed.DB]
a = idx # Location
for e in Ed:
self.ep[e] = -1 # Invalidate all edge positions
x = 4 # set slice edges
for j in Ed:
if a - c_nk(11 - j, x) >= 0:
self.ep[j] = slice_edge[4 - x]
a -= c_nk(11 - j, x)
x -= 1
x = 0 # set the remaining edges UR..DB
for j in Ed:
if self.ep[j] == -1:
self.ep[j] = other_edge[x]
x += 1
def get_slice_sorted(self):
"""Get the permutation and location of the UD-slice edges FR,FL,BL and BR.
0 <= slice_sorted < 11880 in phase 1, 0 <= slice_sorted < 24 in phase 2, slice_sorted = 0 for solved cube."""
a = x = 0
edge4 = [0] * 4
# First compute the index a < (12 choose 4) and the permutation array perm.
for j in range(Ed.BR, Ed.UR - 1, -1):
if Ed.FR <= self.ep[j] <= Ed.BR:
a += c_nk(11 - j, x + 1)
edge4[3 - x] = self.ep[j]
x += 1
# Then compute the index b < 4! for the permutation in edge4
b = 0
for j in range(3, 0, -1):
k = 0
while edge4[j] != j + 8:
rotate_left(edge4, 0, j)
k += 1
b = (j + 1) * b + k
return 24 * a + b
def get_d_edges(self):
"""Get the permutation and location of the edges DR, DF, DL and DB.
0 <= d_edges < 11880 in phase 1, 0 <= d_edges < 1680 in phase 2, d_edges = 0 for solved cube."""
a = x = 0
edge4 = [0] * 4
ep_mod = self.ep[:]
for j in range(4):
rotate_right(ep_mod, 0, 11)
# First compute the index a < (12 choose 4) and the permutation array perm.
for j in range(Ed.BR, Ed.UR - 1, -1):
if Ed.DR <= ep_mod[j] <= Ed.DB:
a += c_nk(11 - j, x + 1)
edge4[3 - x] = ep_mod[j]
x += 1
# Then compute the index b < 4! for the permutation in edge4
b = 0
for j in range(3, 0, -1):
k = 0
while edge4[j] != j + 4:
rotate_left(edge4, 0, j)
k += 1
b = (j + 1) * b + k
return 24 * a + b
def get_u_edges(self):
"""Permutation and location of edges UR, UF, UL and UB.
u_edges < 11880 in phase 1, u_edges < 1656 + 24 in phase 2, u_edges = 1656 for solved cube."""
a = x = 0
edge4 = [0] * 4
ep_mod = self.ep[:]
for j in range(4):
rotate_right(ep_mod, 0, 11)
# First compute the index a < (12 choose 4) and the permutation array perm.
for j in range(Ed.BR, Ed.UR - 1, -1):
if Ed.UR <= ep_mod[j] <= Ed.UB:
a += c_nk(11 - j, x + 1)
edge4[3 - x] = ep_mod[j]
x += 1
# Then compute the index b < 4! for the permutation in edge4
b = 0
for j in range(3, 0, -1):
k = 0
while edge4[j] != j:
rotate_left(edge4, 0, j)
k += 1
b = (j + 1) * b + k
return 24 * a + b
