class FifteenPuzzle(Puzzle):
def __init__(self, arg=list(range(1,16))+[0]):
self.mat = Matrix(4,4, list(arg))
def is_valid_state(self):
return list(sorted(self.mat)) == list(range(16))
def is_valid_operation(self, op):
if not (isinstance(op, PermutationOperation) and
len(op.perm.array_form) == 16):
return False
cyc = op.perm.cyclic_form
if len(cyc) == 0:
return True
if not (len(cyc) == 1 and len(cyc[0]) == 2):
return False
a = divmod(cyc[0][0], 4)
b = divmod(cyc[0][1], 4)
if not (self.mat[a] == 0 or self.mat[b] == 0):
return False
dm = a[0]-b[0]
dn = a[1]-b[1]
return dm*dn == 0 and abs(dm+dn) == 1
def __str__(self):
return self.mat.table(StrPrinter())
def __repr__(self):
return str(self)
