rt，一本通 AC 洛谷全 WA。

#include <bits/stdc++.h>

using namespace std;
struct people
{
	int num;
	int time;
}arr[1000001];
bool cmp(people a,people b)
{
	return a.time<b.time;
} 
int main()
{
	int n;
	double time_sum=0,time_average;
	cin>>n;
	memset(arr,0,sizeof(arr));
	for (int i=1;i<=n;i++)
	{
		cin>>arr[i].time;
		arr[i].num=i;
	}
	sort(arr+1,arr+1+n,cmp);
	for (int i=1;i<=n;i++)
	{
		cout<<arr[i].num<<" ";
		if (n-i>=1)
		{
			time_sum+=arr[i].time*(n-i);
		}
	}
	time_average=time_sum/n;
	printf("%.2lf",time_average);
	return 0;
}