Tree: Depth-First Search - Path Sum II (All Root-to-Leaf Paths)
Consider the same iterative DFS code for Path Sum II. What is the output when the tree has a single node with value 0 and targetSum=0?
Consider the same iterative DFS code for Path Sum II. What is the output when the tree has a single node with value 0 and targetSum=0?
medium🧾 Code Trace Q4 of Q15
Step-by-Step Solution
Solution:
Step 1: Initialize stack and pop root
Stack starts with (0,[0],0). Pop it, node is leaf, sum=0 equals target.Step 2: Append path and return
Append [0] to result and return [[0]].Final Answer:
Option B → Option BQuick Check:
Single node equals target sum, path is [0] [OK]
Quick Trick: Single node leaf with sum=target -> path included [OK]
Common Mistakes:
MISTAKES- Returning empty list for single node
- Appending extra zeros to path
Trap Explanation:
PITFALL- Candidates may forget to handle single-node trees correctly or confuse leaf condition.
Interviewer Note:
CONTEXT- Tests edge case handling and correctness of leaf detection.
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