A live coding interview is a session where you solve a programming problem in real time while an interviewer watches, usually in a shared editor such as CoderPad or HackerRank, or occasionally in your own IDE over a screen share. Sessions typically run 45 to 60 minutes and cover one or two problems with follow-up extensions.
What Live Coding Interview means in practice
The interviewer states a problem, often with deliberately incomplete requirements, and expects you to clarify before coding. A typical shape is five minutes of clarification and examples, ten on approach and complexity, twenty five to thirty five on implementation, then testing and extensions. Autocomplete and syntax highlighting are often limited in shared pads, and at some companies code is never executed, so you may be asked to trace it by hand. Scoring covers correctness, complexity, code structure, testing instinct and how clearly you communicate under time pressure. It appears at the technical screen stage and again inside most onsite loops.
Why it matters for candidates
Live coding measures thinking out loud as much as coding, so the same solution scores very differently depending on how it was reached. Interviewers want requirements clarified, an approach stated before typing, complexity discussed honestly and edge cases tested without prompting. Practicing silently in your own configured editor builds the wrong reflex; practice out loud, with someone watching, on a keyboard without your usual shortcuts.
How to prepare
- Restate the problem and confirm edge cases before coding.
- State your approach and its complexity, then start typing.
- Talk through what you are writing as you write it.
- Trace a small example by hand at the end.
- Practice in a plain shared editor, not your configured IDE.
Example
The prompt is to find the first non-repeating character in a string. The candidate asks about Unicode, empty input and case sensitivity, settles on ASCII and case sensitive, then states the plan aloud: one pass to count occurrences, one pass to find the first count of one, linear time and constant extra space for a fixed alphabet. They write it in ten minutes, trace it against a two character example, then answer a follow-up about streaming input.
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