前缀和+暴力=TLE
#include<iostream>
using namespace std;
int A[100005];
int main(){
int n,f;
double ans=0;
scanf("%d%d",&n,&f);
for(int i=1;i<=n;i++){
scanf("%d",&A[i]);
A[i]+=A[i-1]; //求前缀和
}
for(int len=f;len<=n;len++) //枚举区间长度
for(int i=0,j=i+len;j<=n;i++,j++){ //枚举区间开头,根据长度得到结尾
ans=max(ans,double(A[j]-A[i])/len);
//cout<<(A[j]-A[i])/len<<" "<<double(A[j]-A[i])/len<<endl;
//输出6 6.16667
}
printf("%d",int(ans*1000));
}