56 lines
1.8 KiB
Python
56 lines
1.8 KiB
Python
class Model:
|
|
Man = "M"
|
|
Wolf = "W"
|
|
Sheep = "S"
|
|
Cabbage = "C"
|
|
def __init__(self, left, right):
|
|
self.left = set(left)
|
|
self.right = set(right)
|
|
|
|
def __eq__(self,other):
|
|
return other.left == self.left and other.right == self.right
|
|
|
|
def __repr__(self):
|
|
return "(%s,%s)" % ( repr(self.left), repr(self.right))
|
|
|
|
def pretty(self):
|
|
return ",".join(self.left) + " <-> " + ",".join(self.right)
|
|
|
|
class Simulator:
|
|
invalid_states = [ set({Model.Wolf,Model.Sheep}), set({Model.Sheep, Model.Cabbage}) ]
|
|
|
|
def simulate(self, state, stack=[]):
|
|
stack = stack + [state]
|
|
if state.right == set([Model.Man,Model.Wolf,Model.Sheep,Model.Cabbage]):
|
|
return stack
|
|
|
|
nextStates = []
|
|
if Model.Man in state.left:
|
|
for obj in state.left:
|
|
nextStates.append( Model(state.left - set([Model.Man,obj]) , state.right | set([Model.Man,obj]) ) )
|
|
else:
|
|
for obj in state.right:
|
|
nextStates.append( Model(state.left | set([Model.Man, obj]) , state.right - set([Model.Man,obj]) ) )
|
|
|
|
nextStates = filter(
|
|
lambda s: not(
|
|
s in stack or
|
|
any([ any([ invalid_state <= m for invalid_state in Simulator.invalid_states ]) and Model.Man not in m for m in [s.left,s.right] ])
|
|
)
|
|
, nextStates) #Remove invalid and previous states.
|
|
|
|
for s in nextStates:
|
|
m = self.simulate(s,stack)
|
|
if m is not None:
|
|
return m
|
|
|
|
return None
|
|
|
|
|
|
if __name__ == "__main__":
|
|
sim = Simulator()
|
|
result = sim.simulate(Model([Model.Man, Model.Wolf, Model.Sheep, Model.Cabbage],[]))
|
|
i = 0
|
|
for state in result:
|
|
print("%d: %s" % (i,state.pretty()))
|
|
i+=1
|