Kotak Bank Interview Experience

Round 1: Bar Raiser round

Coding Question:

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's.

Input: matrix = [[1,1,1],[1,0,1],[1,1,1]] Output: [[1,0,1],[0,0,0],[1,0,1]]

Input: matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]

Output: [[0,0,0,0],[0,4,5,0],[0,3,1,0]]

Constraints:

m == matrix.length n == matrix[0].length 1 <= m, n <= 200 -2^31 <= matrix[i][j] <= 2^31 - 1

class Solution {
    public int[][] solve(int[][] input) {
        
        int m = input.length;
        int n = input[0].length;

        // boolean[] rows = new boolean[m];
        // boolean[] cols = new boolean[n];

        boolean firstRow = false;
        boolean firstCol = false;
        for(int i = 0; i < m; i++) {
            for(int j = 0; j < n; j++) {
                if (input[i][j] == 0) {
                    if(i == 0) {
                        firstRow = true;
                    }
                    if (j == 0) {
                        firstCol = true;
                    }
                    input[i][0] = 0;
                    input[0][j] = 0;
                }
            }
        }

        for(int i = 1; i < m; i++) {
            for(int j = 1; j < n; j++) {
                if (input[i][0] == 0 || input[0][j] == 0) {
                    input[i][j] = 0;
                }
            }
        }

        if(firstRow) {
            for(int j = 0; j < n; j++) {
                input[0][j] = 0;
            }
        }

        if (firstCol) {
            for(int i = 0; i < m; i++) {
                input[i][0] = 0;
            }
        }

        return input;
    }
}

class Main {

    public static void main(String[] args) {
        // int[][] input = {
        //     {1,1,1},
        //     {1,0,1},
        //     {1,1,1}
        // };

        int[][] input = {
            {1,0,0},
            {2,3,4},
            {5,6,7}
        };

        /*
[
 [1, 0, 0],
 [2, 3, 4],
 [5, 6, 7]
]
[
 [1, 2, 0],
 [3, 4, 0],
 [5, 6, 7]
]
[
 [1, 2, 3, 4],
 [5, 0, 7, 8],
 [0,10,11,12],
 [13,14,15,0]
]
         */

        // int[][] input = {
        //     {0,1,2,0},
        //     {3,4,5,2},
        //     {1,3,1,5}
        // };

        Solution solution = new Solution();
        input = solution.solve(input);

        for(int i = 0; i < input.length; i++) {
            for (int j = 0; j < input[i].length; j++) {
                System.out.print(input[i][j] + " ");
            }
            System.out.println();
        }
    }
}

LLD

Online Marketplace - Buy & Sell Products

Prompt: Design the backend components for an online marketplace where users can buy and sell products. Consider features such as user authentication, product listing, search functionality, shopping cart, and order management.

🔸 Sub-components to explore: User Authentication – Signup, Login, JWT-based session Product Listing – Sellers can create, update, delete, and view listings Search Functionality – Full-text search and filtering Shopping Cart – CRUD operations on items Order Management – Placing, viewing, and cancelling orders

Distributed Architecture Questions:

1. Explain how you would ensure data consistency across multiple nodes in a distributed database.
2. Discuss the challenges and techniques for handling distributed session management.
3. Explain the role of distributed messaging systems like Kafka or RabbitMQ in a backend system.