Question

How do I create a method that takes a two-dimensional array as a parameter and displays the index of the row with the most zeros? The program I have does compile. It just displays an incorrect result. The method countZeros() counts the number of zeros in each row. I need to compare each count with the next, so I created count and count2. The location of the greater count will be stored in rowNum. I’m not sure what I am doing wrong. I think it may be indexing incorrectly.

Here is my code:

public class P118 
{

    public static void main(String[]args)
    {

        int[][]num = {{0,3,6,0,0}, {1,3,8,9,8}, {9,9,9,0,8}, {3,7,9,9,9}}; 

    System.out.print(rowWithMostZeros(num));

    }

    public static int rowWithMostZeros(int[][]arr)
    {
        int count = 0, count2 = 0, rowNum = -1;

        for(int row = 0; row<arr.length;row++)
        {

            count = countZeros(arr[row]);

            if(count>count2)
            {

            rowNum = row;
            }

        }
        for(int i=0; i<arr.length;i++)
        {

            count2 = countZeros(arr[i]);

        }

        return rowNum;
    }
    public static int countZeros(int[]x)
    {
        int count = 0;

        for(int i = 0; i<x.length;i++)
        {
            if(x[i]==0)
            {
              count++;

            }
        }


        return count;
    }

}

Answer 1

Try this:

public static int rowWithMostZeros(int[][] arr) {

    if (arr == null || arr.length < 1) {
        return -1;
    }

    int rowWithMostZeros = 0;
    int count = countZeros(arr[0]);

    for (int i = 1; i < arr.length; i++) {
        int count2 = countZeros(arr[i]);
        if (count2 > count) {
            rowWithMostZeros = i;
        }
    }

    return rowWithMostZeros;
}

public static int countZeros(int[] arr) {
    int count = 0;
    for (int i = 0; i < arr.length; i++) {
        if (arr[i] == 0) {
            count += 1;
        }
    }
    return count;
}