How to Prepare for a Coding Interview

Coding interviews are stressful, but they're predictable. Most interviews test the same concepts. With the right preparation, you can walk in confident and walk out with an offer.

What Companies Actually Test

Companies don't just check if you can solve the problem. They look at:

• Problem-solving approach — How you break down the problem
• Communication — Can you explain your thinking?
• Coding ability — Is your code clean and correct?
• Testing — Do you consider edge cases?

The 4-Week Preparation Plan

Week 1: Data Structures

• Arrays and Strings
• Linked Lists
• Hash Maps (most important)
• Stacks and Queues

Week 2: Algorithms

• Two Pointers
• Sliding Window
• Binary Search
• Recursion basics

Week 3: Practice Problems

• Solve 2-3 problems daily on LeetCode
• Focus on easy and medium difficulty
• Time yourself (30-45 minutes per problem)

Week 4: Mock Interviews

• Practice with a friend
• Use Pramp or Interviewing.io for free mock interviews
• Review and learn from mistakes

The Most Common Interview Patterns

Most coding interview problems fall into these patterns:

// Pattern 1: Frequency Counter
// Count occurrences of elements
function isAnagram(s, t) {
  if (s.length !== t.length) return false;
  const count = {};
  for (let char of s) {
    count[char] = (count[char] || 0) + 1;
  }
  for (let char of t) {
    if (!count[char]) return false;
    count[char]--;
  }
  return true;
}

// Pattern 2: Two Pointers
// Use two pointers moving toward each other
function twoSum(nums, target) {
  const map = new Map();
  for (let i = 0; i < nums.length; i++) {
    const complement = target - nums[i];
    if (map.has(complement)) return [map.get(complement), i];
    map.set(nums[i], i);
  }
  return [];
}

Behavioral Questions

Technical skills aren't enough. Prepare for questions like:

• "Tell me about a time you disagreed with a teammate"
• "What's your biggest weakness?"
• "Why do you want to work here?"

Use the STAR method: Situation, Task, Action, Result. Prepare 3-5 stories from your experience.

Day of the Interview

• Get a good night's sleep
• Arrive 10 minutes early (or join the call 5 minutes early)
• Think out loud — explain your approach before coding
• Ask clarifying questions
• Test your code with examples before saying you're done

What If You Fail?

Failing an interview is normal. Even top developers get rejected. Learn from the experience, practice more, and try again. Many companies have multiple interview rounds — failing one doesn't mean failing all.