I'm stuck on a problem where I am supposed to make a method that returns the row with the highest average number in a 2D array

The method that I attached here only gets the averages of each row. I believe that I need to keep track the row with the highest average but I just don't know how Any suggestions?

int[][] array = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };

public static double getRowAverage(int grid[][]) {
    int i, j;
    double sum = 0, average = 0;
    for (i = 0; i < grid.length; i  ) {
        for (j = 0; j < grid[i].length; j  ) {
            sum = sum   grid[i][j];
        }
        average=sum/grid[i].length;
        System.out.println("Average of row "   (i 1)   " = "   average); 
        sum=0;
        double a = i 1;
    }
    return average;
}

CodePudding user response：

You can compare and check if the row average is higher than the current highest

double rowAverage = sum / grid[i].length;
average = rowAverage > average ? rowAverage : average;

or even better, use Math.max

average = Math.max(average, sum / grid[i].length);

CodePudding user response：

Some notes regarding the code in your question.

• As well as sum, you also need to zero average for each new row.
• No need to declare loop variables i and j outside of the loop.
• Java has "short-circuit" statements like =.
• I understand that the purpose of this line:

double a = i 1;

is to store the index of the row (in the grid) that contains the highest average. That variable should be int (and not double) since a row index can only be an int. The variable should also be declared outside of the outer for loop since you can only know its final value after you have processed all the rows in grid. In the code below, I renamed a to maxRow.

• You need another variable to store the maximum.

public class Averages {

    public static void main(String[] args) {
        int[][] grid = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
        double maxAvg = 0.0;
        int maxRow = -1;
        for (int i = 0; i < grid.length; i  ) {
            double sum = 0, average = 0;
            for (int j = 0; j < grid[i].length; j  ) {
                sum  = grid[i][j];
            }
            average = sum / grid[i].length;
            if (average > maxAvg) {
                maxAvg = average;
                maxRow = i;
            }
            System.out.println("Average of row "   (i 1)   " = "   average);
        }
        System.out.println("Row with highest average: "   (maxRow   1));
    }
}

When I run the above code, I get the following output:

Average of row 1 = 2.0
Average of row 2 = 5.0
Average of row 3 = 8.0
Row with highest average: 3