Given a binary tree where each root-to-leaf path represents a number formed by concatenating node values, which algorithmic approach guarantees computing the sum of all such numbers efficiently without missing any path or double counting partial paths?
easy🔍 Pattern Recognition Q11 of Q15
Tree: Depth-First Search - Sum Root to Leaf Numbers
Given a binary tree where each root-to-leaf path represents a number formed by concatenating node values, which algorithmic approach guarantees computing the sum of all such numbers efficiently without missing any path or double counting partial paths?
ADepth-first search (DFS) that accumulates the current number along the path and adds it only at leaf nodes
BDynamic programming that stores sums for subtrees and combines them at the root
CGreedy traversal that sums node values at each level independently
DBreadth-first search (BFS) that sums values of nodes at each depth and multiplies by depth
Step-by-Step Solution
Step 1: Understand problem requirements
The problem requires summing numbers formed by concatenating node values from root to leaf, so partial paths must not be summed prematurely.
Step 2: Identify correct traversal pattern
DFS naturally explores root-to-leaf paths, allowing accumulation of the current number and summing only at leaf nodes, ensuring correctness.
Final Answer:
Option A -> Option A
Quick Check:
DFS accumulates path values correctly and sums only at leaves [OK]
Quick Trick:Sum only at leaves during DFS traversal [OK]
Common Mistakes:
MISTAKES
Summing at non-leaf nodes
Using BFS without path tracking
Trap Explanation:
PITFALL
Greedy or BFS approaches seem simpler but fail to track full root-to-leaf paths correctly.
Interviewer Note:
CONTEXT
Tests if candidate can identify correct traversal pattern for path-based tree problems.
Master "Sum Root to Leaf Numbers" in Tree: Depth-First Search
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