33 lines
833 B
Python
33 lines
833 B
Python
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import random
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class ListDict(object):
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def __init__(self):
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self.item_to_position = {}
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self.items = []
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def add_item(self, item):
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if item in self.item_to_position:
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return
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self.items.append(item)
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self.item_to_position[item] = len(self.items)-1
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def remove_item(self, item):
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position = self.item_to_position.pop(item)
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last_item = self.items.pop()
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if position != len(self.items):
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self.items[position] = last_item
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self.item_to_position[last_item] = position
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def choose_random_item(self):
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return random.choice(self.items)
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def __contains__(self, item):
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return item in self.item_to_position
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def __iter__(self):
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return iter(self.items)
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def length(self):
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return len(self.items)
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