[Solved] Given a binary tree and a target sum, you want to find the total number of paths where the sum of node values equals the target.... Which technique is most suitable to solve this efficiently? | Tree: Depth-First Search

Tree: Depth-First Search - Path Sum III (Any Path)

Given a binary tree and a target sum, you want to find the total number of paths where the sum of node values equals the target. Paths must move only from parent nodes to child nodes. Which technique is most suitable to solve this efficiently?

ABreadth-first search with level order traversal

BDepth-first search with prefix sum hash map

CDynamic programming with memoization on node values

DSorting node values and using two pointers

Step-by-Step Solution

Solution:

Step 1: Use DFS traversal to explore all downward paths
Traverse the tree using DFS to explore all downward paths from parent to child nodes.
Step 2: Maintain prefix sums in a hash map for efficient lookup
Keep track of cumulative sums from root to current node to quickly find if a subpath sums to target.
Final Answer:
Option B -> Option B
Quick Check:
Prefix sums enable O(n) time complexity [OK]

Quick Trick: Use DFS with prefix sums for downward path sums [OK]

Common Mistakes:

MISTAKES

Using BFS which doesn't track path sums efficiently
Trying to sort node values which breaks tree structure
Applying DP without considering path direction

Trap Explanation:

PITFALL

BFS and sorting ignore path direction and structure, leading to incorrect results.

Interviewer Note:

CONTEXT

Tests understanding of algorithmic patterns for path sum problems in trees.

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Which technique is most suitable to solve this efficiently?

Step 1: Use DFS traversal to explore all downward paths

Step 2: Maintain prefix sums in a hash map for efficient lookup

Final Answer:

Quick Check:

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