Path Sum III

Med
Code
Loading editor...
Tap Analyze to see visualization
Variables

Run code to see variables

Output

Console output will appear here

Press Space to start•← → to step•? all shortcuts

Solution Guide: Path Sum III

Approach

For each node, count paths starting there plus recurse into all descendants as new starts.

Complexity Analysis

Time
O(n^2) worst-case (simple DFS variant)
Space
O(h) recursion depth

Pattern

Root-Any-to-Any Path Sums

Why It Works

Every node can be a path start, and each call checks all downward continuations.

Updated Feb 2026