看了讨论,改了精度后还是不行,求助!
#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
int n;
long long a[1005],k[1005];
double sum;
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++){
scanf("%lld",&a[i]);
a[i]=a[i]*1000+i;
}
sort(a+1,a+1+n);
for(int i=1;i<=n;i++){
cout<<a[i]%1000<<" ";
a[i]/=1000;
}
printf("\n");
for(int i=1;i<=n;i++)sum+=(n-i)*a[i];
sum/=n;
printf("%.2f",sum);
return 0;
}