Module Overview: We're going to break down exactly what happens in that 45-60 minute Zoom call. It's not just about getting the right answer; it's about checking specific boxes in the interviewer's mental rubric.

The Interview Flow (45-60 Minutes)

Most technical interviews follow a strict 5-stage structure. Knowing this helps you manage your time and nerves.

  1. Introduction (5 min): Building rapport. Smile, be professional.
  2. Warm-Up (5-10 min): Easy problem to check basics (e.g., Reverse a String).
  3. Main Challenge (25-35 min): The core evaluation. Medium/Hard algorithmic problem.
  4. Follow-Ups (5-10 min): Scaling, optimization, and edge cases.
  5. Your Questions (5 min): Show genuine interest in the team and culture.

Stage 2: The Warm-Up

Think of this like stretching before a workout. The interviewer wants you to succeed. Example: "Reverse a string."

Good Response: Ask clarification ("Handle nulls?"), explain approach ("Two pointers"), write clean code, trace it.
Bad Response: Silence, O(n²) string concatenation, crashing on null.

Stage 3: The Main Challenge

This is the heart of the interview. Example: Two Sum.

"Given an array of integers and a target sum, find two numbers in the array that add up to the target. Return their indices."

The Optimal Approach (O(n) Time)

Start with Brute Force (O(n²)), but quickly identify the bottleneck. For each number, we are looking for its complement (target - number). A HashMap lets us find that complement in O(1). 

public int[] twoSum(int[] nums, int target) {
    // Handle edge case
    if (nums == null || nums.length < 2) {
        return new int[]{};
    }
    
    // Map: number -> index
    Map<Integer, Integer> map = new HashMap<>();
    
    for (int i = 0; i < nums.length; i++) {
        int complement = target - nums[i];
        
        // Check if complement exists
        if (map.containsKey(complement)) {
            return new int[]{map.get(complement), i};
        }
        
        // Store current number
        map.put(nums[i], i);
    }
    
    return new int[]{};
}

This demonstrates Optimal Thinking: Trading space (O(n) for the map) for time (O(n) speed).

The 4 Evaluation Criteria

Interviewers are silently scoring you on these four dimensions.

1. Problem Decomposition

Can you break complex problems into manageable pieces? Don't try to solve the whole thing at once. Identify the core challenge vs. surface details. Recognize patterns (e.g., "This feels like a Sliding Window").

2. Optimal Thinking

Don't settle for the first solution. The progression should be:
Brute Force → Identify Bottleneck → Apply Pattern → Optimal Solution

Know your time complexities. If N = 100,000, an O(n²) solution will timeout. You need O(n) or O(n log n).

3. Clean Coding

Write code for humans, not just compilers.

4. Communication

The Golden Rule: Think Out Loud. A silent genius often fails interviews because the interviewer can't read their mind. Explain your approach, walk through examples, and state your complexity before you even touch the keyboard.

Conclusion

Interviews are a skill separate from daily coding. By understanding the timeline and what interviewers are actually looking for, you can control the signal you send and turn a stressful interrogation into a collaborative conversation.