LeetCode 2236: Root Equals Sum of Children

Meta Data

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Difficulty: easy First Attempt: 2025-12-17

• Submissions: Python Accepted → C++ Compile Error → C++ Accepted

Approach

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The tree is guaranteed to have only a root and two children, so compare root.val with the sum of the two children.

My Attempts

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Python passed on the first try. The C++ rewrite first failed to compile because of a missing semicolon:

return (root->left->val + root->right->val) == root->val    // missing ;

Solution

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class Solution:
    def checkTree(self, root: Optional[TreeNode]) -> bool:
        return root.val == root.left.val + root.right.val

class Solution {
public:
    bool checkTree(TreeNode* root) {
        return root->val == root->left->val + root->right->val;
    }
};

Complexity

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Time O(1), space O(1).

Mistakes to Avoid

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• In C++, access members through a pointer with ->, not ..
• A C++ return statement needs a trailing semicolon.

Interview Explanation

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The tree always has exactly three nodes, so I compare the root value with the sum of its two children. Time and space are O(1).