Step 15: Graphs [Concepts & Problems]›Problems on BFS/DFS
Number of islands
MediumFunction: numberOfIslands()
ASCI Mission Breakdown • Simple as Hell
"Master Number of islands: Take `n` (number) and `edges` (number[][]), execute an optimal problems on bfs/dfs strategy, and return number with clean edge-case handling."
Real-World Metaphor:
Think of Number of islands as an everyday real-world challenge: you receive input data, inspect its elements in sequence without making unnecessary duplicate passes, and transform the collection to reach the exact target without wasting computer memory.
Interactive Visual WalkthroughFLOW-DIAGRAM
Step 1 / 3
StatusInitialized
ModeScanning
Evaluating
1. Initialize State for Number of islands
Load inputs and initialize algorithmic registers.
How to Think About This (Mental Model)
Unpack the problem parameters (`n` (number) and `edges` (number[][])) and clarify what is given vs what must be returned.
Identify the optimal data structure or pattern (e.g. pointers, hash map, or stack) to avoid redundant recalculations.
Walk through state transitions, handle edge cases (empty collections, single items, negative numbers), and return the verified result.
Given `n` nodes and an edge list `edges` representing a network graph, determine the solution for **Number of islands**.
Identify connected components, cycles, or shortest paths.
Examples
Example 1
Input: n = 4, edges = [[0,1],[1,2],[2,3]]
Output: 1
Constraints
1 <= n <= 2000
0 <= edges.length <= 5000
Topic Tags:
Graphs [Concepts & Problems]Problems on BFS/DFSnumberOfIslands