Tree: Depth-First Search - Balanced Binary Tree
The following code attempts to check if a binary tree is balanced using iterative postorder traversal. Which line contains a subtle bug that can cause incorrect results on an empty tree or null root?
The following code attempts to check if a binary tree is balanced using iterative postorder traversal. Which line contains a subtle bug that can cause incorrect results on an empty tree or null root?
medium🐞 Bug Identification Q14 of Q15
Step-by-Step Solution
Solution:
Step 1: Identify handling of empty tree
The code does not check if root is None before starting traversal, which can cause errors or incorrect results.Step 2: Verify other lines
Other lines handle null children safely using heights.get with default 0, and last_visited logic is correct.Final Answer:
Option A -> Option AQuick Check:
Missing early return for empty root causes bug [OK]
Quick Trick: Always check for empty root before traversal [OK]
Common Mistakes:
MISTAKES- Forgetting to handle empty tree as balanced
- Incorrectly comparing last_visited causing infinite loops
- Not defaulting heights for null children
Trap Explanation:
PITFALL- Option A looks like initialization but missing empty check causes subtle bug; others are correct usage.
Interviewer Note:
CONTEXT- Tests if candidate notices edge case handling for empty input in iterative traversal.
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