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The Coding Round

The 45-minute crucible.

Introduction

The coding round is the core of the technical interview. You will face 2 to 3 of these during an onsite loop.

You have 45 minutes to read a problem, devise an algorithm, write the code, and prove that it works. This requires intense focus and a strict adherence to a time management framework.

The 45-Minute Timeline

If you mismanage your time, you will fail, even if you know the answer. Memorize this timeline.

Minutes 0-5: Understand & Clarify

  • The interviewer pastes the prompt. Read it carefully.
  • Ask clarifying questions. "Can the array be empty?" "Are we dealing with negative numbers?"
  • Run through a small example out loud to ensure you understand the expected output.

Minutes 5-15: Propose & Plan

  • State the Brute Force solution quickly. "The naive way is nested loops, which is \(O(N^2)\)."
  • Propose the optimal solution. "We can use a Hash Map to track complements in \(O(N)\) time."
  • CRITICAL: Wait for the interviewer's approval. If they say "Sounds good", proceed. If they say "Can we do better on space?", you must pivot.
  • Write 3 lines of pseudo-code comments.

Minutes 15-35: Implement

  • Write the actual Python code.
  • Talk through your logic as you type. "I'm initializing the dictionary here..."
  • Use clean, descriptive variable names (max_profit instead of m).
  • Do not remain completely silent for more than 2 minutes.

Minutes 35-40: Dry Run & Debug

  • Stop typing. Do not say you are done.
  • Say: "Let me dry run this with the first example."
  • Trace your variables explicitly.
  • Fix any minor bugs (off-by-one errors) you find during the trace.

Minutes 40-45: Complexity & Q&A

  • State the final Big O Time and Space complexity.
  • The interviewer will ask if you have any questions for them. Always have 2 prepared questions about the company or their team's tech stack.

Common Pitfalls

  • Coding too early: If you start writing code at Minute 3 without agreeing on an algorithm, the interviewer might stop you 20 minutes later and say your approach is fundamentally flawed. You will not have time to recover.
  • Silent coding: If you don't talk, the interviewer can't give you hints.
  • Defensiveness: If the interviewer points out a bug, immediately accept it. Do not argue that it "should work".

Key Takeaways

  • The coding round is a test of communication and time management, not just algorithms.
  • Always get verbal approval for your algorithm before writing code.
  • Dry run your code before declaring you are finished.