void apsp(int *shortest, int *distance, int numOfCity)
{
    int  i, j, k;
    int  *s, *d;
    int  x;
    
    s = shortest;
    d = distance;
    for (i = 0; i < numOfCity; i++)
        for (j = 0; j < numOfCity; j++) {
            *s++ = (j != i) ? *d : 0;
            d++;
        }

    for (k = 0; k < numOfCity; k++) {
        s = shortest;
        for (i = 0; i < numOfCity; i++)
            for (j = 0; j < numOfCity; j++) {
                if (*s > (x = *(shortest + i*numOfCity + k) 
                            + *(shortest + k*numOfCity + j)))
                    *s = x;
                s++;
            }
    }
}