Leetcode/src/1261-Find-Elements-in-a-Contaminated-Binary-Tree/1261.cpp at master · jungejg/Leetcode · GitHub

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class FindElements
{
public:
    FindElements(TreeNode* root)
    {
        root->val = 0;
        data.insert(0);
        dfs(root);
    }

    bool find(int target)
    {
        return data.count(target);
    }

private:
    unordered_set<int> data;

    void dfs(TreeNode* root)
    {
        if (root->left)
        {
            root->left->val = 2 * root->val + 1;
            data.insert(root->left->val);
            dfs(root->left);
        }
        if (root->right)
        {
            root->right->val = 2 * root->val + 2;
            data.insert(root->right->val);
            dfs(root->right);
        }
    }
};