Binary Tree Path Sum
Hard
binary-tree
dfs
path-sum
Problem Description
Given a binary tree and a target sum, determine if there exists a root-to-leaf path where the sum of node values equals the target.
Input Format
First line contains target sum. Second line contains space-separated node values in level-order (use -1 for null nodes).
Output Format
Print "YES" if such path exists, "NO" otherwise
Constraints
1 ≤ number of nodes ≤ 1000, -1000 ≤ node values ≤ 1000
Sample Input/Output
Input:
22 5 4 8 11 -1 13 4 7 2 -1 -1 -1 1
Output:
YES
Explanation
Path 5→4→11→2 sums to 22
Solution Hints
- Read carefully: Understand input/output format and constraints
- Start simple: Think of brute force solution first, then optimize
- Edge cases: Consider empty inputs, single elements, max constraints
- Data structures: Choose arrays, hash maps, sets based on problem needs
- Time complexity: Ensure your solution fits within time limits
- Test examples: Verify logic with provided sample inputs
300
Points
Points
2000ms
Time Limit
Time Limit
256MB
Memory Limit
Memory Limit
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