How do you calculate the sum of a tree where each node is the sum of its children?
This problem tests your recursive traversal skills and understanding of tree summation properties.
Why Interviewers Ask This
Interviewers want to see if you can validate tree properties recursively. It checks your ability to aggregate data from subtrees. The problem also tests logical consistency in tree definitions.
How to Answer This Question
Define the base case for leaf nodes. Explain how to sum left and right subtree values. Compare the sum with the current node's value. Return true if consistent for all nodes. Discuss post-order traversal necessity.
Key Points to Cover
- Post-order traversal
- Summing children values
- Leaf node base case
- Global validity check
Sample Answer
I will use post-order traversal. For each node, I calculate the sum of its left and right children. If the node's value equals this sum, I continue; otherwise, I return false. Leaf nodes are valid by default. This ensures the entire tree satisfies the property.
Common Mistakes to Avoid
- Using pre-order traversal incorrectly
- Not handling leaf nodes
- Incorrect sum calculation logic
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