Subset Sum

#include <math.h>
#include <stdio.h>
 
int S[] = {-7, -3, -2, 5, 8};
 
int main()
{
    unsigned int i, n, a, j, nn, ui;
    n = pow(2, sizeof(S) / sizeof(int)) - 1;
    ui = sizeof(S) / sizeof(int);
 
    for (i = 0 ; i <= n ; nn = ++i)
    {
        a = 0;
        for (j = 0 ; j < ui ; ++j, nn >>= 1)
        {
            a += (nn & 0x1) * S[j];
        }

        if (a == 0)
        {
            printf("Sum (at %i)\n", i);
        }
    }
 
    return 0;
}