Tree: Depth-First Search - Path Sum II (All Root-to-Leaf Paths)
What is the space complexity of the recursive backtracking solution for Path Sum II in terms of recursion stack and output storage, given N nodes, path length L, and K valid paths?
What is the space complexity of the recursive backtracking solution for Path Sum II in terms of recursion stack and output storage, given N nodes, path length L, and K valid paths?
medium🪤 Complexity Trap Q6 of Q15
Step-by-Step Solution
Solution:
Step 1: Recursion stack space
Maximum recursion depth equals path length L, so O(L) stack space.Step 2: Output storage space
Storing K paths each of length L requires O(K * L) space.Final Answer:
Option D → Option DQuick Check:
Space = recursion stack + output storage [OK]
Quick Trick: Space = recursion depth + output paths [OK]
Common Mistakes:
MISTAKES- Ignoring recursion stack space
- Assuming output space is O(K) only
Trap Explanation:
PITFALL- Candidates often forget recursion stack space or underestimate output storage size.
Interviewer Note:
CONTEXT- Tests understanding of auxiliary space including recursion and output.
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