PrintLikeAWave.java

// Print Like a Wave
// Send Feedback
// For a given two-dimensional integer array/list of size (N x M), print the array/list in a sine wave order, i.e, print the first column top to bottom, next column bottom to top and so on.
// Input format :
// The first line contains an Integer 't' which denotes the number of test cases or queries to be run. Then the test cases follow.

// First line of each test case or query contains two integer values, 'N' and 'M', separated by a single space. They represent the 'rows' and 'columns' respectively, for the two-dimensional array/list.

// Second line onwards, the next 'N' lines or rows represent the ith row values.

// Each of the ith row constitutes 'M' column values separated by a single space.
// Output format :
// For each test case, print the elements of the two-dimensional array/list in the sine wave order in a single line, separated by a single space.

// Output for every test case will be printed in a seperate line.
// Constraints :
// 1 <= t <= 10^2
// 0 <= N <= 10^3
// 0 <= M <= 10^3
// Time Limit: 1sec
// Sample Input 1:
// 1
// 3 4 
// 1  2  3  4 
// 5  6  7  8 
// 9 10 11 12
// Sample Output 1:
// 1 5 9 10 6 2 3 7 11 12 8 4
// Sample Input 2:
// 2
// 5 3 
// 1 2 3 
// 4 5 6 
// 7 8 9 
// 10 11 12 
// 13 14 15
// 3 3
// 10 20 30 
// 40 50 60
// 70 80 90
// Sample Output 2:
// 1 4 7 10 13 14 11 8 5 2 3 6 9 12 15 
// 10 40 70 80 50 20 30 60 90 

import java.util.Scanner;

public class PrintLikeAWave {

    public static void takeInput(int arr[][], Scanner s) {
        System.out.println("Enter Elements of the array : ");
        int rows = arr.length;
        int columns = 0;
        if (rows != 0) {
            columns = arr[0].length;
        }

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < columns; j++) {
                System.out.println("Enter " + i + "th row " + j + "th column Element");
                arr[i][j] = s.nextInt();
            }
        }
        System.out.println();
    }

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.println("Enter the number of test cases here : ");
        int t = s.nextInt();

        for (int i = 1; i <= t; i++) {
            System.out.println("Enter the rows of the " + i + " Array");
            int rows = s.nextInt();
            System.out.println("Enter the columns of the " + i + " Array");
            int columns = s.nextInt();
            int arr[][] = new int[rows][columns];
            takeInput(arr, s);
            wavePrint(arr);
        }
    }

    public static void wavePrint(int arr[][]) {
        int rows = arr.length;
        int columns = 0;
        if (rows != 0) {
            columns = arr[0].length;
        }

        for (int j = 0; j < columns; j++) {
            if (j % 2 == 0) {
                for (int i = 0; i < rows; i++) {
                    System.out.print(arr[i][j] + " ");
                }
            } else {
                for (int i = rows - 1; i >= 0; i--) {
                    System.out.print(arr[i][j] + " ");
                }
            }

        }
    }
}