The Grind
Over two years, I solved 600+ problems on LeetCode and other platforms. Not because I enjoyed it (some days I hated it), but because the tech hiring system demanded it.
But here's the question nobody asks: did it make me a better engineer?
What DSA Taught Me
1. Pattern Recognition
After solving hundreds of problems, you start seeing patterns everywhere — not just in coding interviews, but in real engineering challenges.
When I needed to find duplicate transactions in a stream of payment events at PhonePe, my mind immediately went to sliding window + hash set. That solution took 30 minutes to implement because I'd solved similar patterns dozens of times.
2. Big-O Thinking
Before DSA grinding, I'd write code that worked and call it done. After, I instinctively think about time and space complexity. "This nested loop is O(n²) — can I do better with a hash map?" became second nature.
This saved us a production incident once. I reviewed a PR that used a nested loop to match user IDs — fine for 100 users in testing, catastrophic for 500,000 users in production.
3. Edge Case Awareness
LeetCode problems are specifically designed to have tricky edge cases — empty arrays, single elements, integer overflow, negative numbers. This trained me to think about edge cases in all code I write.
4. Confidence in Interviews
Let's be honest — the primary practical benefit of DSA grinding is interview performance. I cleared interviews at PhonePe, Glance, and two other top companies. Without DSA prep, I wouldn't have gotten past the first round.
What DSA Didn't Teach Me
1. System Design
Knowing how to reverse a linked list doesn't help you design a notification system for 500M users. System design requires a completely different skill set — understanding trade-offs, distributed systems, databases, caching.
2. Code Maintainability
LeetCode rewards clever, compact solutions. Production code rewards readable, maintainable solutions. These are often opposing forces. I had to unlearn the habit of writing "clever" one-liners.
3. Collaboration
Coding alone on a problem is nothing like working with a team on a codebase that's been evolving for 5 years. Communication, code review, documentation — none of this comes from DSA.
4. Domain Knowledge
No amount of tree traversal problems prepared me for understanding payment flows, fintech regulations, or user behavior patterns. Domain knowledge comes only from working in the domain.
My Honest Assessment
DSA grinding is necessary but not sufficient for a career in tech.
- For interviews: Essential. The system is what it is. Prepare for it.
- For daily engineering: Moderately useful. The thinking patterns transfer, but 80% of my daily work uses concepts I never saw on LeetCode.
- For career growth: Barely relevant. Nobody gets promoted because they can solve hard graph problems. You get promoted for delivering impact.
My Advice
- Do enough DSA to clear interviews — For most people, 200-300 well-chosen problems is sufficient.
- Focus on patterns, not quantity — Understanding sliding window deeply is better than solving 50 random problems.
- Don't neglect real-world skills — System design, communication, and domain expertise matter more for your career than your LeetCode streak.
- Stop when you hit diminishing returns — If you've solved 300+ and aren't improving, your time is better spent on projects.
I don't regret solving 600+ problems. But if I could go back, I'd have stopped at 400 and spent the extra time building side projects and learning system design.