题解 | 牛牛的数学作业

#include <bits/stdc++.h>
using namespace std;
int main() {
    long long t,n;
    cin>>t;
    int arr[200000];
    for(int i=1;i<=t;i++){
        int n;
        long long max=-10000000000,min=10000000000,jicha;
        double average,fangcha,sum=0,pingfanghe=0;
        cin>>n;
        for(int j=1;j<=n;j++){
            cin>>arr[j];
            if(arr[j]>max){
                max=arr[j];
            }
            if(arr[j]<=min){
                min=arr[j];
            }
            sum+=arr[j];
            pingfanghe+=arr[j]*arr[j];
        }
        average=sum/n;
        fangcha=pingfanghe/n-average*average;
        jicha=max-min;
        cout<<jicha<<" "<<fixed<<setprecision(3)<<fangcha<<endl;
    }
    return 0;
}