The best way to prepare for DSA interviews isn't to memorize solutions. It's to understand your code so deeply that you can write it from scratch and debug it in real time. Run your own solution to every classic interview problem and see exactly what it does.
Why LearnBug for interview prep
You can't memorize your way through a FAANG interview. The interviewer will ask follow-up questions, change constraints, or ask you to explain your thinking aloud. LearnBug builds the kind of deep understanding that holds up under pressure — because you've watched your own code solve the problem, not copied a solution.
How to use this section
Start with the Top DSA Questions to understand which problems are most common. Then use the Big O and Time Complexity guides to build analysis intuition. Work through each problem guide, run your own solution on LearnBug, and watch it execute before your interview.
The 30 most commonly asked DSA problems at top companies, each with visual execution walkthroughs and complexity analysis.
See O(n), O(log n), O(n²) in actual execution. Understand why time complexity matters by watching your code's operation count grow.
How to analyze any algorithm's complexity — with real code showing execution count at each step. Learn to read Big O from code instantly.
The single most common interview problem. See why O(n²) is slow, watch the hash map approach work in O(n), and understand the intuition behind it.
Every classic recursion problem with call stack visualization. Factorial, Fibonacci, subsets, permutations — run your own code and watch every frame.
O(log n) search — but the edge cases trip everyone up. Watch low/mid/high converge on the target and understand every boundary condition.
Run both on the same graph and watch the traversal order differ completely. Know instantly which to reach for and why in any interview question.
Write your own code for every problem. Watch it execute — and know you actually understand it.