C++: Easy and Concise
\nclass FindElements {\nprivate:\n    unordered_set<int>st;\n    void makeTree(TreeNode* root,int data)\n    {\n        if(!root) return;\n        root->val=dat
```\nclass FindElements {\nprivate:\n    unordered_set<int>st;\n    void makeTree(TreeNode* root,int data)\n    {\n        if(!root) return;\n        root->val=data;\n        st.insert(data);\n        makeTree(root->left,(data*2+1));\n        makeTree(root->right,(data*2+2));\n            \n    }\n    \npublic:\n    FindElements(TreeNode* root) {\n        makeTree(root,0);\n    }\n    \n    bool find(int target) {\n        return st.find(target)!=st.end();\n    }\n};\n\n```
['Recursion', 'C', 'Ordered Set', 'C++']