Spaced Repetition for Coding Interviews: The Complete Guide

Spaced repetition is the most effective learning technique ever discovered. Medical students use it to memorize thousands of facts. Language learners use it to acquire vocabulary. Yet almost no one applies it to coding interview prep.

This guide explains exactly how to use spaced repetition for DSA study, whether you build your own system or use an existing tool.

What Is Spaced Repetition?

Spaced repetition is a learning technique where you review information at increasing intervals. Instead of reviewing everything every day, you review each item exactly when you are about to forget it.

The Science: Ebbinghaus and the Forgetting Curve

In 1885, German psychologist Hermann Ebbinghaus discovered the forgetting curve. His experiments showed that without reinforcement, we forget roughly 50% of new information within an hour, and nearly 80% within a week. However, each time you successfully recall something, the curve flattens. The memory becomes more durable.

This is why traditional cramming fails for coding interviews. You might memorize the Two Pointers technique on Monday, but by Friday your brain treats it as noise unless you have reinforced it. (Sound familiar? We explore this problem in depth in Why Do I Keep Forgetting LeetCode Solutions?)

Spaced repetition is engineered to exploit this biology. By scheduling reviews right before you would forget, it converts fragile short-term memories into durable long-term ones with minimal total review time.

The animation below visualizes how the SRS algorithm schedules reviews. Notice how the intervals grow exponentially as memory strengthens:

The intervals grow exponentially. If you remember something correctly:

If you forget, the interval resets and starts small again. This ensures you spend time on what you actually need to review, not what you already know.

Why It Works

Spaced repetition exploits two cognitive principles, both of which have been validated by decades of research in cognitive psychology:

The SM-2 Algorithm

Most modern SRS tools, including Anki, use a variant of the SM-2 algorithm, developed by Piotr Wozniak in the late 1980s. The algorithm tracks your performance on each card and adjusts the review interval accordingly:

• If you answer correctly and easily, the interval increases (e.g., 1 day to 3 days to 10 days).
• If you answer correctly but with difficulty, the interval increases more slowly.
• If you answer incorrectly, the card resets to a short interval (starting nearly from scratch).

This adaptive behavior is what makes SRS so efficient. You are not wasting time reviewing things you already know well. Your study time is allocated precisely where it is needed.

How to Apply SRS to DSA

Option 1: Anki or Similar App

The most common approach is using a flashcard app like Anki. Create cards for each pattern or problem you learn:

Anki Setup Best Practices

• Syntax Highlighting — Install an add-on like "Syntax Highlighting for Anki" to make code readable.
• Limit New Cards — Set "New cards/day" to 10. Adding 50 cards a day leads to burnout in week 2.
• Honest Ratings — If you hesitated, press "Hard". If you got it wrong, press "Again". Don't lie to the algorithm.

Option 2: Problem Re-Solving Schedule

Instead of flashcards, you can schedule full problem re-solves:

1. Solve a problem for the first time
2. Re-solve it from scratch 1 day later (no peeking)
3. Re-solve 3 days after that
4. Re-solve 1 week after that
5. Re-solve 2 weeks after that

Track your schedule in a spreadsheet or use a tool like LeetCode's favorite list with date annotations.

Option 3: Integrated Learning Platforms

The ideal solution is a platform that integrates spaced repetition directly into the learning experience, so you do not need to maintain a separate system.

What to Put on Cards

Not everything deserves a flashcard. Focus on high-value items:

Real Example: Merge Intervals

Common Mistakes

1. Making Cards Too Complex

A card should test one thing. If your answer takes 5 minutes to produce, the card is too complex. Break it into smaller pieces.

2. Not Actually Attempting Recall

Spaced repetition only works if you genuinely attempt to recall before seeing the answer. If you flip immediately, you are just reading, not testing.

3. Giving Up on Failed Cards

When you fail a card, that is actually good information. It tells the system you need more practice. Failed cards get scheduled more frequently.

The Time Investment

Once your SRS system is set up, daily reviews take about 15-30 minutes. This small daily investment compounds into massive long-term retention.

Consider the alternative: without SRS, you will inevitably forget. You will sit down to review "Sliding Window" before an interview and realize you have lost it. Then you spend an hour re-learning from scratch. This happens repeatedly, for every pattern. Over a 3-month prep cycle, you might waste 20-40 hours on this "relearning tax."

How TerminalTales Implements SRS

TerminalTales has spaced repetition built directly into the platform:

• Automatic scheduling — The system tracks your learning and schedules reviews automatically.
• Pattern-level cards — Reviews focus on patterns, not individual problems.
• Integrated experience — No need to maintain a separate Anki deck. Reviews happen inside the course.
• Active recall — Reviews require you to produce answers, not just recognize them.

Stop forgetting what you learn. Start using spaced repetition, and your knowledge will compound instead of decay.