AlgoSolveoRoadmap › Stage 6: Trees › Pattern 28 of 53
DSA pattern guide
Tree — BFS / Level Order
Anything "by level": level lists, right view, width, zigzag.
Use it when
Anything "by level": level lists, right view, width, zigzag.
Key idea
Queue the root and process size-of-queue nodes per round. Each round is one level.
Practice problems, in order
- Average of Levels in Binary TreeEasy
- Binary Tree Level Order TraversalMedium
- Binary Tree Zigzag Level Order TraversalMedium
- Binary Tree Right Side ViewMedium
- Vertical Order TraversalMedium
- Maximum Width of Binary TreeMedium
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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