About This Pattern
Master the DFS / BFS pattern by practicing these problems organized by difficulty.Focus on the Key Signals - these are the indicators that tell you when to use this pattern.
Easy (1)
Flood Fill
Perform flood fill starting from pixel [sr, sc], changing connected pixels to new color.
Key Signals:
Connected componentsColor fillGrid traversal
Medium (2)
Number of Islands
Count number of islands in a 2D grid (connected land cells).
Key Signals:
Connected componentsMark visitedDFS/BFS from each unvisited land
Max Area of Island
Find the maximum area of an island in a 2D grid.
Key Signals:
Track area during traversalReturn maxSimilar to count islands