求救！

#include<bits/stdc++.h>
using namespace std;
int n;
double num;
struct a1{
    int l;
    int id;
}a[1001];
bool cmp(a1 b,a1 c){
    return b.l > c.l;
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){cin>>a[i].l;a[i].id=i;}
    sort(a+1,a+n+1,cmp);
    for(int i=n;i>=1;i--){
        num+=a[i].l*(i-1);
        cout<<a[i].id<<" ";
    }
    cout<<endl;
    printf("%.2lf",num*1.0/n);
    return 0;
}