8 Coding Interview Tips That Senior Engineers Swear By
After watching hundreds of candidates fail interviews they should have passed, a pattern emerges. These 8 tips address the most common, fixable mistakes.
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1. Clarify Before You Code
Ask 2-3 clarifying questions before touching code. "Are inputs guaranteed to be non-null?" "Can there be duplicates?" "Should I optimize for time or space?" This signals engineering maturity and often reveals constraints that change your approach entirely.
2. Think Out Loud — Especially When Stuck
Silence is the enemy. Even if you don't know the answer, narrate your thinking: "I'm stuck on the base case... let me think about what the simplest input would be..." Interviewers can coach you through hints. They can't coach a wall of silence.
3. Write the Brute Force First
A working O(n²) solution is worth more than a failed attempt at O(n). Once you have the brute force, you have the logic. Then optimize. Interviewers want to see that you can solve problems, then that you can make them efficient.
4. Test With a Simple Example Before Submitting
Trace through your code manually with a 3-5 element example. Catch off-by-one errors, null pointer cases, and incorrect loop bounds before your interviewer does. It demonstrates rigor.
5. Name Your Variables Clearly
"i" and "j" are acceptable in tight loops, but "leftPointer" and "rightPointer" make your intent clear at a glance. Interviewers are reading your code in real-time — make it easy on them.
6. Handle Edge Cases Explicitly
After your main solution, say: "Let me think about edge cases — empty input, single element, all duplicates, negative numbers." Even if you don't write specific code for each, naming them shows systems thinking.
7. State Your Complexity
Don't wait to be asked. After your solution, say: "This is O(n) time and O(n) space because of the hashmap." If you can improve it, say: "I could reduce space to O(1) by using two pointers instead — want me to refactor?"
8. Practice Writing Code Without an IDE
Your fingers will betray you if you've never coded without autocomplete. Use a plain text editor for at least 50% of your practice problems. Real interviews use Google Docs, CoderPad, or whiteboards — none have IntelliSense.