Interview Experience with Amazon - Technical Round 1 for SDE 2

I recently had the opportunity to interview with Amazon for the role of SDE 2, and I must say, it was an exhilarating experience that truly tested my technical prowess and problem-solving abilities. Here’s a recap of the interview process and the insights gained:

Preparation and Initial Rounds: After successfully clearing the telephonic rounds, I was invited for the Technical Round 1, which aimed to delve deeper into my technical skills and understanding.

Technical Round 1 Overview:

Question 1 - System Design Scenario: The interview began with a discussion on a system design scenario where I was asked to design a scalable and fault-tolerant system architecture for a real-time application handling millions of concurrent users. We discussed various aspects such as load balancing, database choices, caching strategies, and microservices architecture.

Question 2 - Algorithmic Problem: Next, I was presented with a classic algorithmic problem - sorting an array of colors represented by integers (0, 1, 2) in-place to group all 0s, 1s, and 2s together (Dutch National Flag problem). I explained my approach using the two-pointer technique to achieve optimal performance without using extra space.

class Main{

    public static void printColors(int[] arr){   
        System.out.println(Arrays.toString(arr));
    }

    public static void sortColors(int[] arr){

        // Use Two Pointers
        int low = 0;
        int high = arr.length - 1;

        for(int i = 0; i<= high;) {
            // Current element is 0
            if(arr[i] == 0){
                swap(arr, i, low);
                low++;
                i++;
            }
            // // Current element is 2
            else if(arr[i] == 2){
                swap(arr, i, high);
                high--;
              
            }
            // Current element is 1
            else{
                i++;
            }
        }
    }

    public static void swap(int[] arr, int i, int j){
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    public static void main(String[] args){
        int[] arr = {0, 1, 2, 2, 1, 0, 2, 0, 1, 0, 2, 1};
        sortColors(arr);
        printColors(arr);
    }
}

Question 3 - Coding Problem: The interview also included a coding problem where I was asked to rotate a 2D matrix by 90 degrees clockwise. I discussed different approaches, including the efficient in-place rotation method, emphasizing space complexity and time complexity considerations.

public class RotateMatrix {

    public static void rotate(int[][] matrix) {
        int n = matrix.length;
        
        // Step 1: Transpose the matrix
        for (int i = 0; i < n; i++) {
            for (int j = i; j < n; j++) {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[j][i];
                matrix[j][i] = temp;
            }
        }
        
        // Step 2: Reverse each row of the transposed matrix
        for (int i = 0; i < n; i++) {
            int left = 0;
            int right = n - 1;
            while (left < right) {
                int temp = matrix[i][left];
                matrix[i][left] = matrix[i][right];
                matrix[i][right] = temp;
                left++;
                right--;
            }
        }
    }

    public static void printMatrix(int[][] matrix) {
        for (int[] row : matrix) {
            for (int num : row) {
                System.out.print(num + " ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        int[][] matrix = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };


        System.out.println("Original Matrix:");
        printMatrix(matrix);

        rotate(matrix);

        System.out.println("\nMatrix after rotating 90 degrees clockwise:");
        printMatrix(matrix);
    }
}

Behavioral and Technical Depth: Throughout the interview, there was a balanced mix of technical depth and behavioral questions. I was asked about my past experiences where I had to sacrifice technical decisions to meet project deadlines and how I handled such situations effectively while maintaining code quality and project goals.

Conclusion: The interview experience with Amazon was rigorous yet fulfilling. It provided me with an opportunity to showcase my skills, problem-solving abilities, and domain knowledge. The technical depth of the questions and the challenging scenarios presented reinforced my passion for software development and problem-solving.

If you're preparing for a similar interview or have any questions about my experience, feel free to reach out or share your insights in the comments below!

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