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How to Prepare

Pattern-first practice, spaced repetition and how many problems is enough.

The most common preparation mistake is solving hundreds of random problems. You end up recognizing problems you've seen, not solving ones you haven't. Pattern-first practice fixes that.

The method

• Learn one pattern at a time. Read the pattern page, understand the template, and know the signals that point to it.
• Solve 4–6 problems per pattern, from easy to hard, before moving on.
• Mix patterns once you've covered them, so you practice *identifying* the pattern — the hardest part in a real interview.
• Revisit problems you struggled with after 3 days, then a week (spaced repetition).

How many problems is enough?

For most candidates, 100–150 well-chosen problems solved properly beats 500 skimmed. "Properly" means:

• You attempted it for 20–30 minutes before looking at a solution
• You can explain why the optimal approach works
• You could re-solve it from scratch a week later

A suggested order

Practice like it's the interview

• Set a timer — 25 minutes for a medium, 40 for a hard.
• Talk out loud, even alone. Communication is a skill that needs practice.
• Don't run your code until you've traced it by hand. Many interviews don't let you execute code; build the habit of verifying manually.
• Write clean code the first time: real variable names, helper functions, no commented-out experiments.

[!TIP] Keep an error log For each problem you got wrong, write one line: what the key insight was and why you missed it ("didn't think to sort first", "off-by-one in binary search bounds"). Review the log before interviews — it's your personal list of blind spots.

In the final week

• Do 2–3 mock interviews with real interviewers
• Practice the company-specific questions for your target companies
• Re-solve your hardest error-log problems
• Rest the day before. Fatigue costs more than one extra problem gains.