rt，帮忙看看吧，是我读错题了吗

题目

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

#define int long long

using namespace std;

const int N = 1000005;

int n, m;
int a[N], sum[N];
double res = -1.0;

signed main()
{
	scanf("%lld%lld", &n, &m);
	for (int i = 1; i <= n; i ++ ) scanf("%lld", &a[i]), sum[i] = sum[i - 1] + a[i];
	
    for (int i = 1; i <= n; i ++ )
      for (int j = i + m; j <= n; j ++ )
        res = max(res, (sum[j] - sum[i]) * 1.0 / (j - i) * 1000.0);
        
    printf("%lld\n", (int)res);
    return 0;
}