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Number of Islands
BFS/DFS + Visited Marking Pattern · Interactive Visualizer & Interview Guide
Related problems
Same BFS/DFS mental model
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Understand the pattern
Explain to interviewer
Java code
Why BFS?
Complexity
Use the controls to step through the BFS traversal, or click Run all to watch it animate.
Example 1 (1 island)
Example 2 (3 islands)
Land '1'
Water '0'
Current (BFS front)
Visited
Island found
BFS Queue:
0
islands found
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