Floyd's Triangle Reverse

Question

I have to make a Floyd Triangle that prints in this order:

7 8 9 10
4 5 6 
2 3
1

But currently my code print like this:

1
2 3 
4 5 6
7 8 9 10

CODE:

    #include <stdio.h>
int main()
{
  int n, i,  c, a = 1;

  scanf("%d", &n);

  for (i = 1; i <= n; i++)
  {
    for (c = 1; c <= i; c++)
    {
      printf("%d ", a); 
      a++;
    }
    printf("\n");
  }

  return 0;
}

Can someone help me?

Answer 1

Here you are.

#include <stdio.h>

int main(void) 
{
    while ( 1 )
    {
        printf( "Enter a non-negative number (0 - exit): " );
        
        unsigned int n;
        
        if ( scanf( "%u", &n ) != 1 || n == 0 ) break;
        
        int width = 0;
        
        for ( unsigned int tmp = n * ( n + 1 ) / 2; tmp != 0; tmp /= 10 )
        {
            ++width;
        }
        
        putchar( '\n' );
        
        for ( unsigned int i = 0; i < n; i++ )
        {
            unsigned int value = ( n - i ) * ( n - i + 1 ) / 2 - ( n - i - 1 );
            
            for ( unsigned int j = 0; j < n - i; j++ )
            {
                printf( "%*u ", -width, value++ );
            }
            
            putchar( '\n' );
        }
        
        putchar( '\n' );
    }
    
    return 0;
}

The program output might look like

Enter a non-negative number (0 - exit): 10

46 47 48 49 50 51 52 53 54 55 
37 38 39 40 41 42 43 44 45 
29 30 31 32 33 34 35 36 
22 23 24 25 26 27 28 
16 17 18 19 20 21 
11 12 13 14 15 
7  8  9  10 
4  5  6  
2  3  
1  

Enter a non-negative number (0 - exit): 4

7  8  9  10 
4  5  6  
2  3  
1  

Enter a non-negative number (0 - exit): 0