4 Lines only C++ code
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:O(1)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:O(n)\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass MyHashSet {\npublic:\n    int v[1000001]={0};\n    MyHashSet() {\n        \n        \n    }\n    \n    void add(int key) {\n        v[key]=1;\n    }\n    \n    void remove(int key) {\n        v[key]=0;\n    }\n    \n    bool contains(int key) {\n        return v[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```
['Array', 'Hash Table', 'Design', 'Hash Function', 'C++']