Question

How do I modify this to let the user input the size of the matrix? The lowest size is 4 and the largest size is 16.

import java.util.*;

public class Test1

{

     public static void main(String[] args)

     {

int[][] matrix = new int[4][4];    // create 4 by 4 matrix (need user input???)

          // generate 1's and 0's for each each rows and columns

     // and track largest row index with the most ones

        int largestRI = 0;

        int largest = -1;

        for (int i = 0; i < matrix.length; i++)

        {

            int rowCount = 0;

              for (int k = 0; k < matrix[i].length; k++)

              {

                   matrix[i][k] = (int)(Math.random() * 2);

                   rowCount += matrix[i][k];

              }

              if (rowCount > largest)

              {

                   largestRI = i;

                largest = rowCount;

              }

        }

        // find largest column index

        int largestCI = 0;

          largest = -1;

          for (int k = 0; k < matrix[0].length; k++)

          {

              int columnCount = 0;

              for (int i = 0; i < matrix.length; i++)

              {

                   columnCount += matrix[i][k];

              }

              if (columnCount > largest)

              {

                   largest = columnCount;

                   largestCI = k;

              }

        }

      

       // display matrix

       for (int i = 0; i < matrix.length; i++)

       {

           for (int k = 0; k < matrix[i].length; k++)

           {

           System.out.printf("%d", matrix[i][k]);

           }

           System.out.printf("\n");

       }

       System.out.println("The largest row index: " + largestRI);

       System.out.println("The largest column index: " + largestCI);

     }

}

Answer 1

import java.util.Scanner;

public class Test1

{

   public static void main(String[] args)

   {
       int size;
       Scanner sc = new Scanner(System.in);
       while (true) {
           System.out.println("Enter size of matrix: ");
           size = sc.nextInt();
           if (size >= 4 && size <= 16)
               break;
           System.out.println("Error: Invalid size.. Must be between 4-16");
       }

       int[][] matrix = new int[size][size]; // create 4 by 4 matrix (need user input???)

       // generate 1's and 0's for each each rows and columns

       // and track largest row index with the most ones

       int largestRI = 0;

       int largest = -1;

       for (int i = 0; i < matrix.length; i++)

       {

           int rowCount = 0;

           for (int k = 0; k < matrix[i].length; k++)

           {

               matrix[i][k] = (int) (Math.random() * 2);

               rowCount += matrix[i][k];

           }

           if (rowCount > largest)

           {

               largestRI = i;

               largest = rowCount;

           }

       }

       // find largest column index

       int largestCI = 0;

       largest = -1;

       for (int k = 0; k < matrix[0].length; k++)

       {

           int columnCount = 0;

           for (int i = 0; i < matrix.length; i++)

           {

               columnCount += matrix[i][k];

           }

           if (columnCount > largest)

           {

               largest = columnCount;

               largestCI = k;

           }

       }

       // display matrix

       for (int i = 0; i < matrix.length; i++)

       {

           for (int k = 0; k < matrix[i].length; k++)

           {

               System.out.printf("%3d", matrix[i][k]);

           }

           System.out.printf("\n");

       }

       System.out.println("The largest row index: " + largestRI);

       System.out.println("The largest column index: " + largestCI);

   }

}

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