Python solution // Can we do better than boolean array ?
\nclass MyHashSet:\n\n    def __init__(self):\n        self.arr = [False] * 1000000\n\n    def add(self, key):\n        self.arr[key] = True\n\n    def remove(s
```\nclass MyHashSet:\n\n    def __init__(self):\n        self.arr = [False] * 1000000\n\n    def add(self, key):\n        self.arr[key] = True\n\n    def remove(self, key):\n        self.arr[key] = False\n\n    def contains(self, key):\n        return self.arr[key]\n```
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