Which modification to the standard diameter algorithm is necessary to handle this variant correctly?
hard🎤 Interviewer Follow-up Q15 of Q15
Tree: Depth-First Search - Diameter of Binary Tree
Suppose the binary tree nodes can have negative values and you want to find the diameter defined as the longest path in terms of number of edges (ignoring node values). Which modification to the standard diameter algorithm is necessary to handle this variant correctly?
ANo modification needed; the standard diameter algorithm based on heights works regardless of node values.
BModify the algorithm to sum node values along paths and find maximum sum path instead of longest path.
CChange the height calculation to ignore negative nodes by treating them as null nodes.
DUse breadth-first search to find the longest path instead of depth-first traversal.
Step-by-Step Solution
Solution:
Step 1: Recognize diameter depends on path length (edges), not node values.
Negative values do not affect height or path length calculations.
Step 2: Confirm standard height-based diameter algorithm works unchanged.
Heights and diameter calculations rely on structure, so no changes are needed.
Final Answer:
Option A -> Option A
Quick Check:
Diameter depends on edges, not node values [OK]
Quick Trick:Diameter is structural, unaffected by node values [OK]
Common Mistakes:
MISTAKES
Confusing diameter with max sum path
Ignoring negative nodes incorrectly
Switching to BFS unnecessarily
Trap Explanation:
PITFALL
Candidates often confuse diameter with max path sum, leading to unnecessary algorithm changes.
Interviewer Note:
CONTEXT
Tests if candidate distinguishes diameter (edges) from max path sum (values).
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