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