Depth-First Search pattern
Surrounded Regions
Given a grid of X and O cells, flip to X every region of O cells that is fully surrounded, that is, any region not connected 4-directionally to an O on the grid border. Watch it run step by step, then write your own pseudocode and get it checked by AI.
- LeetCode 130
- Medium
- 1 approach
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Depth-First SearchLeetCode 130
Medium
The approach
- 01 Border flood + capture sweep O(R·C)O(R·C) space
What you will learn
- How to read Surrounded Regions and spot the depth-first search pattern in it
- Border flood + capture sweep: O(R·C) time, O(R·C) space
- The pseudocode for each approach, its line lit as the animation runs
- Practice: write your own pseudocode and get it checked
More Depth-First Search
See Surrounded Regions run, step by step
Sign in and this page opens on the animation, with all 18 Depth-First Search problems beside it.
DSA comes with the all labs plan and every ChaiCode batch.