I think my program is correct.


sum = 0;
            fl = 0;
            for (i = len; i > 0; i--)
            {
                if (s[i] == '1')
                {
                    sum += i;
                    fp[i] = ++count;
                }
                else
                    fp[i] = count;
            }
            d = sum%(n+1);
            p = n+1-d;
            if (d == 0)
                printf("%s0\n", s);
            else if (d == 1)
                printf("%s1\n", s);
            else if (p <= count)
            {
                for (i = 1; i <= len; i++)
                {
                    if (fl == 0 && fp[i] == p)
                    {
                        printf("0");
                        fl = 1;
                    }
                    printf("%c", s[i]);
                }
            }
            else
            {
                for (i = 1; i <= len; i++)
                {
                    if (fl == 0 && fp[i]+i == p)
                    {
                        printf("1");
                        fl = 1;
                    }
                    printf("%c", s[i]);
                }
            }