AlgoSolveoRoadmap › Stage 4: Stacks › Pattern 18 of 53
DSA pattern guide
Stack — Monotonic
Next greater/smaller element, spans, largest rectangle.
Use it when
Next greater/smaller element, spans, largest rectangle.
Key idea
Keep a stack sorted increasing or decreasing. When a new item breaks the order, pop and resolve those elements.
Practice problems, in order
- Next Greater Element IEasy
- Next Greater Element IIMedium
- Daily TemperaturesMedium
- Online Stock SpanMedium
- Asteroid CollisionMedium
- Largest Rectangle in HistogramHard
- Maximal RectangleHard
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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