Question

In Java Please Create A Program For The Following;

Please Note: This program should be able accept changes to the values of constants ROWS and COLS when testing the codes.

Switch2DRows
Given a 2D array with ROWS rows and COLS columns of random numbers 0-9, re-order the rows such that the row with the highest row sum is switched with the first row. You can assume that 2D arrau represents a rectangular matrix (i.e. it is not ragged). Sample run:

3 2 4 1
3 9 8 5
6 1 4 9
Largest Row = 1

3 9 8 5
3 2 4 1
6 1 4 9

Required methods:
public static void fillArray(int[][] arr)
// Fills a 2D array with random numbers 0-9

public static void showArray(int[][] arr)
// Displays a 2D array as rows and columns

public static int largestRow(int[][] arr)
// Returns the row with the largest sum

public static int rowSum(int[][] arr, int row)
// Returns the sum for a specific row of a 2D array

public static void largestRowFirst(int[][] arr)
// Switches the 1st row with the row that has the largest sum

    public static void main()
    {
        final int ROWS = 3;
        final int COLS = 4;
        int [][] a2d = new int[ROWS][COLS];

        fillArray(a2d);
        showArray(a2d);
        largestRowFirst(a2d);
        showArray(a2d);
    }
This program should be able accept changes to the values of constants ROWS and COLS when testing your code.

Answer 1

Answer:

Explanation:

Here are all the functions filled fillArray, showArray, largestRow , rowSum and largestRowFirst

largestRowFirst uses the largestRow function to get the index of the largest row

and the largestRow uses the rowSum to get the sum of each row.

Then the largest row is swapped with the first row.

Code:

import java.util.Random;

public class Main
{
  
public static void fillArray(int[][] arr)
{
Random r = new Random();
  
for(int i=0; i<arr.length; i++)
{
for(int j=0; j<arr[i].length; j++)
{
arr[i][j] = r.nextInt(10);
}
  
}
}
// Fills a 2D array with random numbers 0-9

public static void showArray(int[][] arr)
{
for(int i=0; i<arr.length; i++)
{
for(int j=0; j<arr[i].length; j++)
{
System.out.print(arr[i][j]+" ");
}
  
System.out.println();
}
}
// Displays a 2D array as rows and columns

public static int largestRow(int[][] arr)
{
int maxi = -1;
int max = -1;
  
for(int i=0; i<arr.length; i++)
{
if(rowSum(arr, i) > max)
{
max = rowSum(arr, i);
maxi = i;
}
  
}
  
return maxi;
}
// Returns the row with the largest sum

public static int rowSum(int[][] arr, int row)
{
int sum = 0;
for(int j=0; j<arr[row].length; j++)
{
sum = sum + arr[row][j];
}
  
return sum;
}
// Returns the sum for a specific row of a 2D array

public static void largestRowFirst(int[][] arr)
{
int index = largestRow(arr);
  

for(int j=0; j<arr[index].length; j++)
{
int temp = arr[index][j];
arr[index][j] = arr[0][j];
arr[0][j] = temp;
}
}
// Switches the 1st row with the row that has the largest sum

public static void main(String[] args)
{
final int ROWS = 3;
final int COLS = 4;
int [][] a2d = new int[ROWS][COLS];

fillArray(a2d);
showArray(a2d);
largestRowFirst(a2d);
showArray(a2d);
}
}

Output:

5 5 4 2 3 6 5 9 9 3 6 4 3 6 5 9 5 5 4 2 9 3 6 4 ... Program finished with exit code 0 Press ENTER to exit console.

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