Scanner
How you observe the problem: one item, two pointers, a window, a graph frontier, or another lawful way to inspect the evidence.
How It Works
A reasoning environment for solving technical problems before code.
- Problem
- Define the Spaces
- Choose the Scanner
- Choose the Recorder
- Establish the Invariant
- Simulate the Decisions
- Prove the Solution
- Write the Code
Recorder
What information you retain so future decisions are based on evidence instead of memory or guesswork.
Invariant
What must remain true as the state changes, so each decision preserves correctness.
Finalizer
How you know the solution is complete: the condition that closes the investigation and proves the result.
Why Use It
The Simulator moves debugging earlier - from the code to the reasoning.
Make your reasoning visible.
Catch bad assumptions before writing code.
Understand why an algorithm works instead of memorizing it.
Practice explaining solutions for technical interviews.
Build reusable problem-solving habits.
Connect DSA reasoning to larger System Design problems.
Case Files + Simulator
Read the case. Work the case. Prove the solution.
Who It Is For
Built for people who want to produce the reasoning, not just recognize it afterward.
Students
Practice turning problem statements into structured proof.
Developers
Strengthen the habits behind cleaner implementation choices.
Technical interview candidates
Rehearse explaining decisions under pressure.
Engineers strengthening DSA
Connect algorithms to repeatable state and invariant reasoning.
System Design learners
Carry proof-first thinking into larger architectural decisions.
Access
Launch the Simulator
Simulator access follows your Correct Code membership.
The Simulator uses the site's existing plan and entitlement logic. If your account has access, the launch button opens the real Simulator. If not, the site will guide you through the current membership or upgrade flow.
You Don't Learn Problem Solving by Watching Someone Else Solve Problems.
You learn by making the decisions yourself.