题解 | 牛牛的数学作业

#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
int main()
{
    int t;
    cin>>t;
    while(t--){
        long long n,sum1=0,ji;
        long long max=-1,min=1e9;
        double diff,fang,sum2=0,ave;
        cin>>n;
        vector<long long>a(n);
        for(int i=0;i<n;i++){
            scanf("%lld",&a[i]);
            sum1+=a[i];
            if(a[i]<min) min=a[i];
            if(a[i]>max) max=a[i];
        }
        ji=max-min;
        ave=(double)sum1/n;
        for(int i=0;i<n;i++){
            diff=(a[i]-ave)*(a[i]-ave);
            sum2+=diff;
        }
        fang=sum2/n;
        printf("%lld %.3f",ji,fang);
        printf("\n");
    }
    return 0;
}