C++ || EASY MAP
```\n/\n * Definition for a binary tree node.\n * struct TreeNode {\n *     int val;\n *     TreeNode left;\n *     TreeNode right;\n *     TreeNode() : val(0),
```\n/**\n * Definition for a binary tree node.\n * struct TreeNode {\n *     int val;\n *     TreeNode *left;\n *     TreeNode *right;\n *     TreeNode() : val(0), left(nullptr), right(nullptr) {}\n *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}\n *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}\n * };\n */\nclass FindElements {\npublic:\n    int x = 0 ; \n    map<int,int>mp ; \n    void build(TreeNode *root , int x)\n    {\n        if(root == nullptr)\n        {\n            return ; \n        }\n        root->val = x ; \n        mp[x]++ ; \n        build(root->left,2*x+1);\n        build(root->right,2*x+2);\n    }\n    FindElements(TreeNode* root) {\n         build(root,0);\n    }\n    \n    bool find(int target) {\n        if(mp.find(target) != mp.end())\n            return true;\n        return false;\n    }\n};\n\n/**\n * Your FindElements object will be instantiated and called as such:\n * FindElements* obj = new FindElements(root);\n * bool param_1 = obj->find(target);\n */
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