Bubble sort 2d array is incorrect

Question

I'm trying to bubble sort the side diagonal of the matrix by decline, but the elements displayed are wrong. The problem is in indexes, but I do not know how to solve it

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <ctype.h>

int main () {
    double a[100][100];
    int n, m;
    int i, j, b, c;
    srand (time (NULL));
    scanf ("%d", &n);
    scanf ("%d", &m);
    for (  i = 0; i < n; i++)
    {
        for (  j = 0; j < m; j++)
        {
            a[i][j] = 0.09 * (rand () %1000) - 0.5;
        }
    }
    printf ("Array A[N][M]: \n");
    for ( i = 0; i < n; i++)
    {
        printf ("\n");
        for ( j = 0; j < m; j++)
        {
            printf ("%6.0f", a[i][j]);
        }
    }
    printf ("\n");
    printf ("\nElements of the right diagonal are: \n");
    for (j = 0; j < m; j++)
    {
        printf( "%6.0lf", a[n - j - 1][j]);
    }
    printf ("\n");
    printf ("\n Sorted array A[N][M]:");
    for ( i = 0; i < n; i++)
    {
        for ( j = 0; j < (m-1); j++)
        {
            if (a[n - j - 1][j]<a[n-j][j+1])
            {
                int temp = a[n - j - 1][j];
                a[n - j - 1][j] = a[n-j][j+1];
                a[n-j-2][j+1] = temp;
            }
        }
    }
    printf ("\n");
    for ( i = 0; i < n; i++)
    {
        printf ("\n");
        for ( j = 0; j < m; j++)
        {
            printf ("%6.0f", a[i][j]);
        }
    }
    printf ("\nElements of the right diagonal are: \n");
    for (j = 0; j < m; j++)
    {
        printf( "%6.0lf", a[n - j-2][j+1]);
    }
    return 0;
}

The goal is receiving a result of elements of diagonal sorted by a decline: (example)

0.74   4.35   7.05     9.1   6.46     6.6   7.48
   5.41   7.28   4.85     2.8   4.28   7.47   7.87
   5.83   2.73   9.42   7.14   1.38   7.22   1.21
   6.91     3.8   9.51   4.56   8.74   7.43   5.63
   9.65   8.04   1.02   9.71   6.02   5.61   1.15
   2.35   1.04   2.23   4.43   6.45     4.5   4.31
     2.7   5.79   3.33   8.44   6.99   4.79        1
Diagonal :    7.48   7.47   1.38   4.56   1.02   1.04    2.7
Sorted array:
   0.74   4.35   7.05     9.1   6.46     6.6   7.48
   5.41   7.28   4.85     2.8   4.28   7.47   7.87
   5.83   2.73   9.42   7.14   4.56   7.22   1.21
   6.91     3.8   9.51     2.7   8.74   7.43   5.63
   9.65   8.04   1.38   9.71   6.02   5.61   1.15
   2.35   1.04   2.23   4.43   6.45     4.5   4.31
   1.02   5.79   3.33   8.44   6.99   4.79        1
Diagonal :   7.48   7.47   4.56    2.7   1.38   1.04   1.02

Hope for your help!

I managed to try the method given in this video: https://www.youtube.com/watch?v=YqzNgaFQEh8, but didn't succeed

Answer 1

Code has at least these problems:

Not a swap

Mis-coded swap

            int temp = a[n - j - 1][j];
            a[n - j - 1][j] = a[n-j][j+1];
            // a[n-j-2][j+1] = temp;
            a[n-j][j+1] = temp;

Output format

If the goal is to see values to 2 decimal places, (and in columns of 7) use "%7.2g" or "%7.2f", not "%6.0f".

Rather than print a '\n' before a loop, I recommend afterwards.

    // printf ("\n");  // Delete
    for ( j = 0; j < m; j++)
    {
        printf ("%6.0f", a[i][j]);
    }
    // Add
    printf ("\n");