Simulation problems,
and the tell.
The problem describes a process and asks what state it ends in. There is no trick to find. 102 problems in the catalogue carry this tag, from first-week easy to interview hard.
Free to start. Running and submitting a solution never costs credits.
How the pattern actually works.
One mechanism, and the mistake that costs people the problem.
The tell. The problem describes a process and asks what state it ends in. There is no trick to find.
The mechanism. Translate the rules into code exactly, step by step, and keep the state in the simplest structure that holds it. The difficulty is reading comprehension, not algorithms.
What goes wrong. Rushing the statement. These are lost by missing one rule, not by being too slow.
The ones asked most often.
By how often the catalogue records them being set, not by our opinion.
- Spiral MatrixMediumasked at 45 companies
- Diagonal TraverseMediumasked at 5 companies
- Mark Elements on Array by Performing QueriesMediumasked at 2 companies
- Time Needed to Buy TicketsEasyasked at 2 companies
- Watering PlantsMediumasked at 1 companies
- Validate Stack SequencesMediumasked at 1 companies
- Double Modular ExponentiationMediumasked at 1 companies
- Divide a String Into Groups of Size kEasyasked at 1 companies
- Total Distance TraveledEasyasked at 1 companies
- Spiral Matrix IIIMediumasked at 1 companies
Read it, watch it, then solve it.
The order that makes a pattern stick.
Everything in the app, in one place.
Practice, interviews and the tools, all free to start. Swipe to see the rest.
DSA practice
Problems filed under the pattern that solves them, not a sheet.
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DBMS asked the way a panel asks it: indexes, joins, normal forms.
in Core CSOpenOOP round
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in Core CSOpenSystem design
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Real schemas, your query, the rows it returns, and an honest verdict.
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Quant, logical, verbal, DI and technical, timed like the real test.
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A clock, marks per question and hidden tests, like a company's judge.
37 papersOpenAlgorithm visualiser
Watch it run on your own input, one step at a time.
26 algorithmsOpenAI that helps, not solves
Hints one at a time, AI review before a mentor reads it.
100 free creditsOpenResume builder
Build it inside the app, next to the work you practised.
in the appOpenProgress and readiness
One score, and the axis you are weakest on.
tracked dailyOpen
Free to start: 100 AI credits when you sign up and 100 every month. Start free in the app
About simulation problems.
Free to start, no card.
Start practisingHow do I know a problem is a simulation problem?
The problem describes a process and asks what state it ends in. There is no trick to find.
How many simulation problems should I solve?
Enough to stop needing the hint, which is usually ten to fifteen across the levels, not the whole list. The catalogue tags 102, split roughly 42 easy, 51 medium and 9 hard in the sample we show, so work up rather than across.
What goes wrong most often in simulation problems?
Rushing the statement. These are lost by missing one rule, not by being too slow.
Is practising by pattern better than a problem sheet?
A sheet tells you what to solve. A pattern tells you why those problems sit together, which is the part that carries over to the problem you have not seen. That is why the app files every problem under its pattern.