Question

For a given integer, n, I need to print all the lists of length 3 which sum to n. The members of the list must be non-negative integers. After printing all these lists, it must then print the number of lists that were found.

For example, if n=2:

• 1+0+1 = 2
• 1+1+0 = 2
• 0+1+1 = 2
• 2+0+0 = 2
• 0+0+2 = 2
• 0+2+0 = 2

Here is the program I did for lists of length 2 rather than lists of length 3:

#include <stdio.h>
int main (void)
{
    int total;
    int c1=0;
    int c2=0;
    int c3=0;
    int count;

    printf("Welcome friends and mainly enemies to the thingy. Only postive intergers!!!\n That's right just enter a number here:");
    scanf ("%d",&total);
    printf ("\n\n\nWhy pick %d? Here is the list if combinations anyway,",total);

    for (count=0;count<=total;count++)
    {
        printf ("\n");
        for (c1=count;c1==count;c1--)
        {
            printf("%d ",c1);

        }
        for (c2=total-count;c2<=total-count;c2++)
        {
            printf("%d",c2);

        }

    }
    printf ("\n\nThere are %d number combinations that total %d",count,total);

}

The goal is to extend this from lists of length two to lists of length 3.

Additional Info:
I can only use one other variable c3.

Answer 1

Hope this helps:

int c3 = 0;
for (int c1 = 0; c1 <= total; c1++) {       
    for (int c2 = total - c1; c2 >= 0; c2--){
        printf("%d %d %d \n", c1, c2, total - c1 - c2);
        c3++;
    }

}

printf("there are %d ways to sum to %d", c3, total);