AlgoSolveoRoadmap › Stage 8: Graphs › Pattern 36 of 53
DSA pattern guide
Graph — BFS
Shortest path in an unweighted grid or graph, multi-source spread (rotting oranges).
Use it when
Shortest path in an unweighted grid or graph, multi-source spread (rotting oranges).
Key idea
Queue with a visited set. Push all sources first for multi-source. Each layer adds one to the distance.
Practice problems, in order
- 01 MatrixMedium
- Clone GraphMedium
- Rotting OrangesMedium
- Shortest Path in Binary MatrixMedium
- Word LadderHard
How to practise this pattern
- Read the problem and look for the signal above before writing any code.
- Say the brute force out loud, with its time complexity, then ask what work it repeats.
- Apply the key idea and write the optimised version yourself.
- If you're stuck for more than 10 minutes, take one small hint, not the full solution.
- Move to the next problem only when you can explain why this pattern fits.
Stuck on one of these?
The AlgoSolveo extension (free, launching soon) sits beside the LeetCode problem and gives the smallest hint that gets you moving, never the full answer. Solved problems tick off on your roadmap.
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