题解 | 牛牛的数学作业

#include <climits>
#include <iostream>
#include <iomanip>
#include <vector>
using namespace std;

int main() {
    int T=0,n=0;
    cin >> T ;
    double variance =0;
    double sum1=0.0,sum2=0.0,average=0.0;
    for(int i=0;i<T;i++)
    {
        double variance =0;
        double sum1=0.0,sum2=0.0,average=0.0;
        int max=0;
        int min=INT_MAX;
        cin >> n ;
        vector<int>arr(n,0);
        for(int j=0;j<n;j++)
        {
            cin >> arr[j] ; 
        }
        for(int j=0;j<n;j++)
        {
            if(arr[j]>max) max=arr[j];
            if(min>arr[j]) min=arr[j];
        }
        cout << max-min <<" ";
        for(int i=0;i<n;i++) 
        {
            sum1 += arr[i];
        }
        average = sum1/n;
        for (int i = 0; i < n; i++)
        {
	        sum2 +=(arr[i] - average) * (arr[i] - average);
        }
        variance = sum2 / n;
        cout << fixed << setprecision(3) << variance << endl;
    }
}