搞不明白了，求大佬看看

#include<stdio.h>
int main()
{
    int remain = 0;
    int i;
    int a[12];
    int sum = 0;
    double huan;
    for (i = 0; i < 12; i++)
    {
        scanf_s("%d\n", &a[i]);
    }
    for (i = 0; i < 12; i++)
    {
        remain = remain + 300 - a[i];
        if (remain / 100 > 0)
        {

            sum = (remain / 100) * 100 + sum;
            remain = remain - sum;
        }
        if (remain  < 0)
        {  printf("-%d", i + 1);
        break; }
        else 
        {
            huan = sum * 1.2+remain;
            printf("%f", huan);
        }
    }
    return 0;
}