Tree: Depth-First Search - Binary Tree Postorder Traversal
What is the space complexity of the recursive postorder traversal on a binary tree with n nodes in the worst case?
What is the space complexity of the recursive postorder traversal on a binary tree with n nodes in the worst case?
medium🪤 Complexity Trap Q6 of Q15
Step-by-Step Solution
Solution:
Step 1: Analyze recursion stack usage
In worst case (skewed tree), recursion depth is n -> O(n) stack space.Step 2: Consider balanced tree case
Balanced tree recursion depth is O(log n), so average space is O(log n), but worst case dominates.Final Answer:
Option D -> Option DQuick Check:
Space depends on recursion depth, worst case O(n) [OK]
Quick Trick: Recursion stack depth = tree height [OK]
Common Mistakes:
MISTAKES- Ignoring recursion stack space
- Assuming constant space
Trap Explanation:
PITFALL- Candidates often forget recursion stack space and assume only output list counts, underestimating space complexity.
Interviewer Note:
CONTEXT- Tests understanding of recursion stack space vs output space
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