Tree: Depth-First Search - Symmetric Tree (DFS Approach)
Consider the edge case of an empty tree (root = None). What does the optimized recursive DFS function return?
Consider the edge case of an empty tree (root = None). What does the optimized recursive DFS function return?
medium🧾 Code Trace Q4 of Q15
Step-by-Step Solution
Solution:
Step 1: Check root condition
Since root is None, the function returns True immediately without recursion.Step 2: Understand base case meaning
An empty tree is symmetric by definition, so returning True is correct.Final Answer:
Option D -> Option DQuick Check:
Empty tree is symmetric [OK]
Quick Trick: Empty tree is symmetric by definition [OK]
Common Mistakes:
MISTAKES- Expecting False for empty tree
- Not handling None root properly
Trap Explanation:
PITFALL- Candidates sometimes forget base case and think empty tree is asymmetric or causes error.
Interviewer Note:
CONTEXT- Tests candidate's understanding of base cases in recursion
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