| class orderedset(object): | |
| def __init__(self): | |
| self.items = [] | |
| self.set = set() | |
| def add(self, item): | |
| if item in self.set: | |
| return False | |
| self.items.append(item) | |
| self.set.add(item) | |
| return True | |
| def pop(self): | |
| item = self.items.pop() | |
| self.set.remove(item) | |
| return item |