题解

#include<bits/stdc++.h>
using namespace std;
int awa[1005];
int qwq;
double pwp;
int main(){
cin>>qwq;
for(int qwp=1;qwp<=qwq;qwp++){
cin>>awa[qwp];
}
sort(awa+1,awa+1+qwq);
for(int qwp=1;qwp<=qwq;qwp++){
pwp+=(qwq-qwp)*awa[qwp];
}
printf("%.2f",pwp/qwq);
return 0;
}