Tree: Depth-First Search - Diameter of Binary Tree
The following code attempts to compute the diameter of a binary tree. Identify the subtle bug that causes incorrect diameter calculation.
The following code attempts to compute the diameter of a binary tree. Identify the subtle bug that causes incorrect diameter calculation.
medium🐞 Bug Identification Q7 of Q15
Step-by-Step Solution
Solution:
Step 1: Check variable scope
Diameter is assigned inside nested function without nonlocal keyword, so outer diameter is not updated.Step 2: Effect on diameter calculation
Diameter remains 0, causing incorrect final result.Final Answer:
Option B -> Option BQuick Check:
Missing nonlocal causes diameter updates to fail [OK]
Quick Trick: Missing nonlocal -> diameter not updated
Common Mistakes:
MISTAKES- Forgetting nonlocal in nested functions
- Assuming diameter updates persist without scope declaration
Trap Explanation:
PITFALL- Candidates overlook variable scope, thinking diameter updates inside nested function affect outer variable.
Interviewer Note:
CONTEXT- Tests understanding of Python variable scope in recursive functions
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