🥇EASY || C++ || BEGINNER FRIENDLY || QUEUE || LEVEL ORDER TRAVERSAL || MAP ✅✅
Code
# Code
```cpp []
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class FindElements {
    unordered_map<int,bool> mp;
public:
    FindElements(TreeNode* root) {
        if(root == NULL){
            return;
        }

        queue<TreeNode*> q;
        root->val = 0;
        q.push(root);

        while(!q.empty()){
            TreeNode * temp = q.front();
            mp[temp->val] = true;
            q.pop();

            if(temp->left){
                temp->left->val = temp->val*2 + 1;
                q.push(temp->left);
            }

            if(temp->right){
                temp->right->val = temp->val*2 + 2;
                q.push(temp->right);
            }
        }
    }
    
    bool find(int target) {
        if(mp[target] == true){
            return true;
        }else{
            return false;
        }
    }
};

/**
 * Your FindElements object will be instantiated and called as such:
 * FindElements* obj = new FindElements(root);
 * bool param_1 = obj->find(target);
 */
```
['Hash Table', 'Tree', 'Queue', 'Binary Tree', 'C++']