Tree: Depth-First Search - Path Sum
What is the space complexity of the recursive DFS with early stopping solution for the Path Sum problem on a balanced binary tree with height h?
What is the space complexity of the recursive DFS with early stopping solution for the Path Sum problem on a balanced binary tree with height h?
medium🪤 Complexity Trap Q6 of Q15
Step-by-Step Solution
Solution:
Step 1: Identify recursion stack usage
Recursive DFS uses call stack proportional to tree height h.Step 2: Consider auxiliary space
Auxiliary space is O(h), and for balanced tree h = O(log n).Step 3: Combine for total space
Space complexity is O(h), which is O(log n) for balanced trees.Final Answer:
Option B -> Option BQuick Check:
Space proportional to recursion depth -> O(h) [OK]
Quick Trick: Recursive stack depth = tree height -> O(h) space [OK]
Common Mistakes:
MISTAKES- Assuming O(n) space for recursion
- Ignoring recursion stack space
Trap Explanation:
PITFALL- Candidates often forget recursion stack space and pick O(1) or O(n) incorrectly.
Interviewer Note:
CONTEXT- Tests understanding of recursion stack space in DFS.
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