homework 1 coded by kazma

import java.util.*;

public class App {

    static int num = 10; // 數組個數

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        // int[] arr = new int[] { 45, 46, 74, 12, 32, 74, 50, 3, 87, 24 }; 
        int[] arr = new int[num];
        int tot=0, rnd = 100; //總和 亂數最大值 紀錄people目前長度

        Random randomObject = new Random(); // create random object
        for (int n=0; n < num; n++) //產生亂數測資
            arr[n] = randomObject.nextInt(rnd);


        for(int n=0; n<num; n++){ //數組加總
            // arr[n] = sc.nextInt();
            tot += arr[n];

        }System.out.println();

        Arrays.sort(arr); //數組排序
        System.out.println(Arrays.toString(arr)); //Debug印出數組
        
        double arg = (double)(tot)/(double)(num);// 平均數

        //眾數
        //  暫存相同數長度  目前最大相同數長度  最大數長度代表的數字
        int peopleLen = 0, peopleLenMax = 0, peopleMax = 0;
        for(int i = 0; i<arr.length-1; i++){
            //若目前數字=下一個數字
            if(arr[i] == arr[i+1]){
                peopleLen += 1; //暫存相同數+1
            }
            // 當暫存相同數長度 > 目前最大相同數長度
            else if(peopleLen > peopleLenMax){
                peopleLenMax = peopleLen; // 目前最大相同數長度=暫存相同數長度
                peopleMax = arr[i]; //紀錄最大數長度代表的數字
                peopleLen = 0; // 暫存相同數歸零
            }
            else //目前數字!=下一數字 而且 暫存相同數長度 < 目前最大相同數長度
                peopleLen = 0;
        }

        double[] quar = new double[3]; //四分位數
        quar[1] = midNum(arr); // 中位數
        quar[0] = midNum(Arrays.copyOfRange(arr, 0, arr.length/2));
        quar[2] = midNum(Arrays.copyOfRange(arr, arr.length%2==0 ? arr.length/2 : arr.length/2+1, arr.length));
            
        double diff = 0; // 差平方和
        //標準差
        for(int i=0; i<num; i++){
            diff += Math.pow((arr[i] - arg), 2);
        }

        System.out.println(String.format("最大值: %d\t最小值: %d\t中位數: %.1f", arr[num-1], arr[0], quar[1]));
        if (peopleLen != peopleLenMax)
            System.out.println(String.format("眾數為: %d", peopleMax));
        else
            System.out.println("此數組不存在眾數!!");
        System.out.println(String.format("樣本標準差為 %.3f\t算術平均數為 %.3f\t", Math.pow(diff/num, 0.5), arg));
        System.out.println(String.format("四分位數: %.1f %.1f %.1f", quar[0], quar[1], quar[2]));
        System.out.println(String.format("四分位距: %d\t", (int)(quar[2] - quar[0])));

        sc.close();
    }

    public static double midNum(int[] arr){ //取中位數
        int num = arr.length;
        double mid, temp = (arr[num / 2] + arr[(num / 2) - 1]);
        if (num % 2 == 0)
            mid = (temp / 2);
        else
            mid = arr[(num / 2)];
        return mid;
    }
}