题解 | 牛牛的数学作业

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int T = in.nextInt();
        while(T-->0){
            int n = in.nextInt(),sum = 0;
            double s = 0;
            int[] nums = new int[n+5];
            for(int i=1;i<=n;i++){
                nums[i] = in.nextInt();
                sum += nums[i];
            }
            Arrays.sort(nums,1,n+1);
            int h = nums[n]-nums[1];
            double v = (double)sum/(double)n;
            for(int i=1;i<=n;i++){
                s += Math.pow(((double)nums[i]-v),2);
            }
            s = s/(double)n;
            System.out.printf("%d %.3f\n",h,s);
        }
    }
}