Technical interviews often don’t go wrong because you “don’t know enough.” They go wrong because you don’t show your thinking clearly under pressure. Here’s a simple, repeatable routine you can practice in 30 minutes a few times a week to boost performance in coding interviews—especially on the “easy/medium” questions that decide many outcomes.

The 30-minute routine (do this like a workout)

1) 5 minutes: Understand + restate the problem

Before you touch code, practice saying:

• Inputs/outputs (types, sizes, constraints)
• Example walkthrough (use a small case)
• Edge cases: empty input, duplicates, negatives, overflow

Tip: If you can’t restate the problem crisply, you’re not ready to code.

2) 8 minutes: Choose an approach and justify it

Pick an approach and explicitly compare it to alternatives.

• “Brute force would be O(n²). We can do better with a hash map for O(n).”
• Name your data structure and why it fits: hash map, two pointers, stack, heap, BFS/DFS, etc.

Interview signal: You’re demonstrating decision-making, not just memorization.

3) 12 minutes: Implement with checkpoints

Write code in small chunks and narrate what you’re doing.

• Start with function signature + helper structures
• Add core loop
• Add conditionals
• Add return

Use micro-checks:

• “At this line, seen contains all elements up to i-1.”
• “This pointer only moves forward, so total moves are O(n).”

Tip: If you go silent while coding, interviewers can’t score your reasoning.

4) 5 minutes: Test like a debugger, not a hopeful optimist

Run through at least:

• The given example
• A minimal edge case
• A tricky case that targets your approach (e.g., duplicates for hash sets)

Close with:

• Time complexity
• Space complexity
• One possible improvement or tradeoff

A quick “talk track” you can reuse

When stuck, say:

• “Let me confirm constraints—are negatives allowed? What’s max n?”
• “I’m going to start with a simple approach, then optimize.”
• “I’ll sanity-check with a small example to verify invariants.”

Common pitfalls this routine prevents

• Jumping into code without clarifying
• Over-engineering before confirming constraints
• Missing edge cases
• Getting flustered and going quiet

Challenge

Pick one classic problem (Two Sum, Valid Parentheses, Longest Substring Without Repeating Characters) and do this routine 3 times this week. Track where you lose time: understanding, approach choice, implementation, or testing.

What part of the coding interview do you struggle with most right now—understanding the prompt, choosing the right data structure, or translating the idea into bug-free code?