sorting elements in a row in a 2D array

Question

I have to sort elements in each row and then display the array.

For example, if the input array is:

             5 1 3                  1 3 5
   INPUT:    7 6 4        OUTPUT:   4 6 7
             9 8 2                  2 8 9

My code for that was:

for (int i = 0; i < size; i++) { //"size" is the size of the square matrix 
    for (int j = 0; j < size; j++) {
        for (int k = 0; k < size - 1; k++) {
            for (int l = 0; l < size - k - 1; l++) {
                if (arr[i][j] > arr[i][j+1]) { //arr[][] is of datatype int
                    int temp = arr[i][j];
                    arr[i][j] = arr[i][j+1];
                    arr[i][j+1] = temp;
                }
            }
        }
    }
}

Any suggestions?

Is your code not working? If not, what output is it producing? (Thanks for providing expected output!) — Trojan
– Trojan, Commented Dec 28, 2013 at 7:27
do you have to implement your own sorting algorithm???... Can you use inbuilt sort methods??? — TheLostMind
– TheLostMind, Commented Dec 28, 2013 at 7:27
I have to implement own sorting methods, and the output it is producing is: 6 7 3 6 7 4 9 8 2 — Kartik
– Kartik, Commented Dec 28, 2013 at 7:33

Diljit PR · Accepted Answer · 2013-12-28 07:55:09Z

5

for (int i = 0; i < size; i++){ //"size" is the size of the square matrix 
    for (int j = 0; j < size; j++){
        for (int k = j+1; k < size; k++){
           if (arr[i][j] > arr[i][k]){ //arr[][] is of datatype int
                  int temp  =  arr[i][j];
                  arr[i][j] =  arr[i][k];
                  arr[i][k] =  temp;
            }

         }
     }
}

I don't think you need 4th loop

edited Dec 28, 2013 at 7:55

Diljit PR

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answered Dec 28, 2013 at 7:34

Ashish

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4 Comments

Kartik Over a year ago

um, what were your loop variables?

Ashish Over a year ago

@user3140017 loop variables not understood what you are asking?

Kartik Over a year ago

oh, sorry about that, my internet connection had a prob, so couldn't see the full code of yours. And, yes its working, Thank You very Much!! Can u please tell me how u came up with this logic?

chrsblck Over a year ago

@user3140017 Most importantly, really spend some time and make sure you fully understand this simple sorting algorithm. Maybe even diagram each step on a piece paper...

Evgeniy Dorofeev · Accepted Answer · 2013-12-28 07:29:20Z

4

I would do it simpler

    for(int[] r : arr){
        Arrays.sort(r);
    }

answered Dec 28, 2013 at 7:29

Evgeniy Dorofeev

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1 Comment

Michael Yaworski Over a year ago

It's homework so he can't use Arrays.sort(array). But this idea of sorting one row at a time is definitely the better solution.

Michael Yaworski · Accepted Answer · 2013-12-28 08:03:41Z

I would create a method to sort rows, and then just iterate through the rows in the matrix and sort them one at a time. For example:

public static int[] sortRow(int[] row) // selection sort
{
    for (int i = 0; i < row.length - 1; i++) {
        for (int j = i + 1; j < row.length; j++) {
            if (row[i] > row[j]) {
                int temp = row[i];
                row[i] = row[j];
                row[j] = temp;
            }
        }
    }
    return row;
}

public static void main(String args[]) 
{
    int[][] arr = {{5, 1, 3}, {7,6,4}, {9,8,2}};

    for (int r = 0; r < arr.length; r++) { // for every row in the matrix
        arr[r] = sortRow(arr[r]); // set the row to be the sorted row
    }

    // print out the array to the console
    for (int r[] : arr) {
        for (int c : r)
            System.out.print(c + " ");
        System.out.println();
    }
}

Output:

1 3 5 
4 6 7 
2 8 9

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