来自黑马程序员Java课程p68、p72、p73、p74

复制数组

package leetcode;

import java.util.Scanner;

public class itheima_p72 {
    public static void main(String[] args) {
        int[] arr = {0,1,2,3,4,5,6,7,8,9,};
        System.out.println("请依次输入你想复制的数组索引,第一个数组为开头，第二个数组为结尾: ");
        Scanner sc = new Scanner(System.in);
        int from = sc.nextInt();
        Scanner ac = new Scanner(System.in);
        int to = ac.nextInt();
        int arr3[] = copyOfRange(arr,from,to);
        for (int i = 0; i < arr3.length; i++) {
            int a = arr3[i];
            System.out.print(a+" ");
        }
    }
    public static int[] copyOfRange(int[] arr,int from,int to){
        int index = 0;
        int newArr[] = new int[to - from];
        for (int i = from; i < to; i++) {
            newArr[index] = arr[i];
            index++;
        }
        return newArr;
    }
}

求质�?

前面好像也写过一个求质数的，只不过那个是键盘录入来求质数，跟这这个不太一样，这道题一样也是来自黑马程序员Java课程

package leetcode;
/*
判断101-200之间有多少个质数并打印出�?/
 */
public class itheima_p72_2 {
    public static void main(String[] args) {
        int number = 0;
        for (int i = 101; i <= 200; i++) {
            boolean flag = true;
            for (int j = 2; j < i; j++) {
                if(i % j == 0){
                    flag = false;
                    break;
                }
            }
            if(flag == true){
                System.out.println(i+"为质�?");
                number++;
            }
        }
        System.out.println("一共有"+number+"个质�?");
    }
}

开发验证码

这里生成随机大小写字母需要用到ASCII码来进行转换，来将大小写字母进行存储到数组中，对其进行随机抽取即�?

package leetcode;

import java.util.Random;

public class itheima_p72_3 {
    public static void main(String[] args) {
        char[] chs = new char[52];
        for (int i = 0; i < chs.length; i++) {
            if (i <= 25) {
                chs[i] = (char) (97 + i);//例如a的ASCII码为97,则第一次循环为97+0=97,转换后即为a
            } else {
                chs[i] = (char) (65 + i - 26);//同理
            }
        }
        for (int i = 0; i < chs.length; i++) {
            //System.out.print(chs[i] + " ");
        }
        String result = "";
        Random r = new Random();
        for (int i = 0; i <= 3; i++) {
            int index = r.nextInt(chs.length);
            //System.out.print(chs[index]+" ");
            result = result + chs[index];
        }
        int number = r.nextInt(10);
        //System.out.println(number);
        result = result + number;
        System.out.print("生成验证码为: "+result);
    }
}

评委打分

package leetcode;

import java.util.Scanner;

public class itheima_p72_4 {
    public static void main(String[] args) {
        int arr1[] = getScore();
        System.out.print("\n最大得分为:" + getMax(arr1));
        System.out.print("\n最小得分为:" + getMin(arr1));
        int result = (getSum(arr1) - getMax(arr1) - getMin(arr1)) / (arr1.length-2);
        System.out.print("\n最终平均得分为: " + result);
    }

    public static int getSum(int arr[]) {
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum = sum + arr[i];
        }
        return sum;
    }


    public static int[] getScore() {
        int[] arr = new int[6];
        System.out.println("请输入老师们的六个评分:");
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i < arr.length; ) {
            int score = sc.nextInt();
            if (score >= 0 && score <= 100) {
                arr[i] = score;
                i++;
            } else {
                System.out.println("成绩超出范围，请重新录入，当前录入成绩为�?" + (i + 1) + "�?");
            }
        }
        return arr;
    }

    public static int getMax(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 getMin(int arr[]) {
        int min = arr[0];
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] < min) {
                min = arr[i];
            }
        }
        return min;
    }
}