C++ :

#include <cstdlib>
#include <cstdio>
#include <algorithm>
using namespace std;
struct person{
	int id;
	int time;
}a[102];
int comp(const person a,const person b)
{
	return a.time<b.time;
}
int main()
{
	int n;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		a[i].id=i;
		scanf("%d",&a[i].time);
	}
	sort(a+1,a+n+1,comp);
	int sum=0;bool first=0;
	for(int i=1;i<=n;i++)
	{
		if(first==0)
		{
			printf("%d",a[i].id);
			first=1;
		}
		else
			printf(" %d",a[i].id);
		sum+=(n-i+1)*a[i].time;
		
	}
	printf("\n%.2lf",(double)(sum/n));
	return 0;
}