Graph Valid Tree

1. 1
   Learn the pattern

   Grid or network traversal → BFS for shortest path, DFS for connectivity/shape. Track visited on push.

2. 2
   Trace your version

   Paste your solution into the workspace and watch every step execute.

   Open workspace
3. 3
   Solve it

   Note: submitting this one needs a LeetCode premium subscription — the pattern is still worth studying.

   Solve on LeetCode Mark solved