Find Elements in a Contaminated Binary Tree LeetCode solution in C++

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class FindElements {
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 public:
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  unordered_map<int, int> m;
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  FindElements(TreeNode *root) {
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    if (root) {
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      root->val = 0;
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      queue<TreeNode *> q;
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      q.push(root);
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      m[0]++;
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      while (!q.empty()) {
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        TreeNode *temp = q.front();
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        q.pop();
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        int x = temp->val;
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        if (temp->left) {
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          temp->left->val = x * 2 + 1;
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          m[x * 2 + 1]++;
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          q.push(temp->left);
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        }
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        if (temp->right) {
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          temp->right->val = x * 2 + 2;
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          m[x * 2 + 2]++;
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          q.push(temp->right);
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        }
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      }
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    }
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  }
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  bool find(int target) {
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    return (m.find(target) != m.end());
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  }
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};