你如何找到二维数组中的最大行

Question

Create 2-D array say m :

1. Ask the user to input row and column sizes from keyboard (use Scanner). N IS 9, if the user input column size is bigger than N+4 ask the user to reinput the column size
2. Fill all arrays elements as double numbers in the range of (3.0 , 13.0) by using of random object

3. Pass the above array m and call the following two methods

   • In findMaxRow(double[][]array) , find and print the largest sum of columns in the 2D array
   • In returnAvg(m) , print out the avg of array m

Comment:

So, I made the the code to find the max Colm but I can't figure out how to find the max Row. I need to be able to find the Max Row but I am figuring out how to since my code finds the cllm and not the max row.

Here is my code:import java.util.Scanner;

  public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    Random rand = new Random();

    System.out.print("Number of Rows? ");
    int rows = input.nextInt();
    System.out.print("Number of Columns? ");
    int columns = input.nextInt();
    while (columns > 7) { // check for column > n+5 where n = 2 in my case
        System.out.print("The column amount is too high. Try another number: ");
        columns = input.nextInt();
    }

    double[][] m = new double[rows][columns];

    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < columns; j++) {
            m[i][j] = rand.nextDouble()*7+4;
        }
    }
    findMaxCol(m);
    System.out.println("The average value of this array is "+returnAvg(m));
}
public static void findMaxCol(double[][] a) {
    double[] maxCol = new double[a[0].length];
    double max = 0;
    int maxColNum=0;
    for (int i = 0; i < a[0].length; i++) { // Sum of Columns
        for (int j = 0; j < a.length; j++) {
            maxCol[i]+=a[j][i];
        }
    }
    //System.out.println(Arrays.toString(maxCol));
    for (int i = 0; i < maxCol.length; i++) {
        if (max < maxCol[i]) {
            max = maxCol[i];
            maxColNum = i; // column number will associate with its array column starting with 0
        }
    }
    System.out.println("The highest column sum is Column #"+maxColNum+" with a sum of "+max);
}
public static double returnAvg(double[][] a) {
    double sum = 0; // initialization
    for (int i = 0; i < a.length; i++) {
        for (int j = 0; j < a[i].length; j++) {
            sum+=a[i][j];
        }
    }
    // System.out.println(sum); Test line
    return (sum/(a.length*a[0].length)); // avg
}

}

Answer 1

Not sure I understand your desired result, but this should give you the row with the greatest sum, as well as what that sum was. Note this doesn't take into account multiple rows with equal sums. It will report the first row in the array with the greatest sum.

public static void findMaxRow(double[][] a){

    double maxSum = 0;
    int maxRow = 0;

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

        double rowSum = 0;

        for (int column = 0; column < a[row].length; column++){
            rowSum += a[row][column];
        }

        if (rowSum > maxSum){
            maxSum = rowSum;
            maxRow = row;
        }
    }

    // maxSum should be the greatest sum of any row
    // maxRow is the row that contained the greatest sum
}