#include <bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	int T[n],s[n];
	double ans;
	for(int i = 0;i<n;i++){
		cin>>T[i];
		s[i] = T[i];
	}
	sort(T , T+n);
	for(int i = 0;i<n;i++){
		for(int j = 0;j<n;j++){
			if(T[i] == s[j]){
				cout<<j+1<<" ";
				s[j] = -1; 
			}
		}
	}
	cout<<endl;
	for(int i = 0;i<n;i++){
		T[i]*=n-i-1;
		ans+=T[i];
	}
	cout<<fixed<<setprecision(2)<<ans/n;
	return 0;
}

上面82分代码 求大神求助一下