C# BitArray
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\npublic class MyHashSet\n        {\n            BitArray arr;\n\n            public MyHashSet()\n            {\n                arr = new BitArray(1000001);\n            }\n\n            public void Add(int key)\n            {\n                arr[key] = true;\n            }\n\n            public void Remove(int key)\n            {\n                arr[key] = false;\n            }\n\n            public bool Contains(int key)\n            {\n                return arr[key];\n            }\n        }\n\n        /**\n         * Your MyHashSet object will be instantiated and called as such:\n         * MyHashSet obj = new MyHashSet();\n         * obj.Add(key);\n         * obj.Remove(key);\n         * bool param_3 = obj.Contains(key);\n         */\n```
['C#']