Chrome

#include<bits/stdc++.h>
using namespace std;
const int N = 100001;
int n;
struct stu{
	double t;
	int id;
}a[N];
bool cmp(stu aa,stu bb)
{
	return aa.t < bb.t;
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;++i)
	{
		cin>>a[i].t;
		a[i].id = i;
	}
	sort(a+1,a+1+n,cmp);
	for(int i=1;i<=n;++i)
	{
		cout<<a[i].id<<" ";
	}
	cout<<endl;
	double sum1=0,sum2=0;
	for(int i=1;i<n;i++)
	{
		sum1 = sum1 + a[i].t;
		sum2 = sum2 + sum1;	
	} 
	printf("%.2f",sum2/n);
	return 0;
}