def minValue(GS, d, p, a, b):
if GS.allPigsEscapedOrCaptued():
return GS.nPigsEscaped()
v_best = float("inf")
v = v_best
successors = GS.allNextStatesWithMoves()
if len(successors) == 0:
return GS.nPigsEscaped()
topAction = successors.keys()[0]
for move, successor in successors.items():
if (p == GS.numPigs):
if (d == self.maxDepth - 1):
v = heuristics.sumPigDistanceToEdge(successor)
else:
v = maxValue(successor, d, a, b)
else:
v = minValue(successor, d, p + 1, a, b)
if v < v_best:
v_best = v
topAction = move
if v_best < a:
return v_best
b = min(b, v_best)
if (d == 0):
return topAction
else:
return v_best
def play(self, GS):
if GS.isEscaped(self.pigId) or GS.isCaptured(self.pigId):
GS.incrementTurn()
return
root = minimaxNode(GS, None)
current = root
while True:
if current is None:
break
if current.simpleDepth >= self.maxDepth * len(GS.players):
# we're at max depth
# so just evaluate with heuristic
# and move on to sibling node
current.favoriteChildValue = heuristics.sumPigDistanceToEdge(
current.GS)
if current.parent is None:
break # have finished exploring
# recurse up the tree
current = current.parent
newCurrent = current.nextNode()
else:
# expand child nodes
current.addChildren(current.GS.allNextStates())
newCurrent = current.nextNode(
) # get next child (down a level)
# no more children of this node left to explore
while newCurrent is None:
# find favorite child for subtree we're done with
if current.GS.isPigTurn():
compare = 'min'
else:
compare = 'max'
current.findBestChild(compare)
if current.parent is None:
break # have finished exploring
# recurse up the tree
current = current.parent
newCurrent = current.nextNode()
current = newCurrent
move = root.favoriteChild.GS.lastMove
GS.movePig(move, self.pigId)
def playOriginal(self, GS):
root = minimaxNode(GS, None)
current = root
a =float("-inf")
b=float("inf")
while True:
if current is None:
break
if current.simpleDepth >= self.maxDepth*len(GS.players):
# we're at max depth
# so just evaluate with heuristic
# and move on to sibling node
current.favoriteChildValue = heuristics.sumPigDistanceToEdge(current.GS)
if current.parent is None:
break # have finished exploring
# recurse up the tree
current = current.parent
newCurrent = current.nextNode()
else:
# expand child nodes
current.addChildren(current.GS.allNextStates())
newCurrent = current.nextNode() # get next child (down a level)
# no more children of this node left to explore
while newCurrent is None:
# find favorite child for subtree we're done with
if current.GS.isPigTurn():
compare = 'min'
else:
compare = 'max'
current.findBestChild(compare)
a, b = current.findBestChildPruned(compare, a, b)
if current.parent is None:
break # have finished exploring
# recurse up the tree
current = current.parent
newCurrent = current.nextNode()
current = newCurrent
move = root.favoriteChild.GS.lastMove
GS.placeBlock(move)