Java0715/Java0715/src/main/java/com/sf/javase/day03/ArrayWorker.java

package com.sf.javase.day03;

import org.junit.jupiter.api.Test;

import java.util.Arrays;

/**
 * 数组练习题
 */
public class ArrayWorker {
    /**
     * 数组统计：求总和、均值
     * 求数组元素的总乘积
     */
    @Test
    public void t1(){
        int[] arr = {4,5,6,1,9};
        int sum = 0;
        int result = 1;
        double avg = 0.0;
        //sum   avg
        for (int i = 0;i<arr.length;i++){
          sum +=  arr[i];
            result *= arr[i];
        }
        System.out.println(sum);
        avg =sum/arr.length;
        System.out.println(avg);
        System.out.println(result);
    }

    /**
     * 求数组元素的最大值
     */
    @Test
    public void t2(){
        int[] arr = {4,5,6,1,9};
        int max = arr[0];
        for (int  i = 0;i<arr.length;i++){
            if(arr[i]>max){
                max = arr[i];
            }
        }
        System.out.println(max);
    }


    /**
     *    找最值大及其所有最大值的下标
     */
    @Test
    public void t3(){
        int[] arr = {4,5,9,1,9,9,3};
        int max = arr[0];
        int count = 0;
        int pre = 0;
        int[] arr1 = new int[arr.length];   //null  0
        String index  = "0";
        for (int i = 0; i < arr.length; i++) {
         if(arr[i] > max){
             max = arr[i];
             pre = max;
             arr1[count] = i;
         }else if (arr[i] == max){
             if(pre != max){
                 count--;
             }
             arr1[++count] = i;
         }
        }
        System.out.println(max);
        System.out.println(index);
        System.out.println(Arrays.toString(arr1));
    }

    @Test
    public void t4(){
        int[] scores = {5,4,6,8,9,0,1,2,7,3};
        int max = scores[0];
        int min = scores[0];
        int sum = 0;
        for (int i = 0; i < scores.length; i++) {
            if (scores[i] > max) {
                max = scores[i];
            }
            if (scores[i] < min) {
                min = scores[i];
            }
            sum += scores[i];
        }
        double avg = (sum - max -min)*1.0/(scores.length-2);
        System.out.println("总分"+sum);
        System.out.println("最高分"+max);
        System.out.println("最低分"+min);
        System.out.println("平均分"+avg);
    }
}