题解 | 牛牛的数学作业

import java.util.Scanner;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);

        int n = sc.nextInt();//输入试卷的张数
        for (int i = 0; i < n ; i++) {
             int num = sc.nextInt();//输入每张试卷的数字个数
            int[] arr = new int[num];
            for (int j = 0; j <num ; j++) {
                int x = sc.nextInt();
                arr[j] = x;
            }
            //找出最大值
            int maxRe = returnMax(arr);
            //找出最小值
            int minRe = returnMin(arr);
            //计算极差
            int lim = maxRe - minRe;

            //接受平均值
            double avg = returnAvg(arr);
            //计算方差
             double sum = 0.0;
            for (int j = 0; j <arr.length ; j++) {

                double l = arr[j] - avg;
                sum += l*l;
            }
            System.out.printf("%d ",lim);
            System.out.printf("%.3f\n",sum/num);
  
        }
    }
    public static int returnMax(int []arr){
        int max = arr[0];
        for (int i = 0; i <arr.length ; i++) {
            if(arr[i]>max){
                max = arr[i];
            }
        }
        return max;
     }
     public static int returnMin(int []arr){
        int min = arr[0];
         for (int i = 0; i < arr.length ; i++) {
             if(arr[i]<min){
                 min = arr[i];
             }
         }
         return min;
     }
     public static double returnAvg(int []arr){
        double sum = 0.0;
        for (int i = 0; i <arr.length ; i++) {
             sum += arr[i];
         }
        return sum/arr.length;
     }
}