Java — jia

3-1

public class Task1 {
    public static void main(String[] args) {
        int[] monthList = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};//十二月份
        int sum = 0;
        Scanner input = new Scanner(System.in);
        System.out.println("请输入某年某月某日：");
        System.out.print("年：");
        int year = input.nextInt();
        System.out.print("月：");
        int m = input.nextInt();
        System.out.print("日：");
        int d = input.nextInt();
        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
            for (int i = m - 1; i > 0; i--) {
                sum = sum + monthList[i - 1];
            }
            if (m > 2) {
                sum += 1;//闰年2月多一天
            }
        } else {
            for (int i = m - 1; i > 0; i--) {
                sum = sum + monthList[i - 1];
            }
        }
        sum += d;//月份的天数加上日子的天数
        System.out.println(year + "年" + m + "月" + d + "日" + "是这一年的第" + sum + "天");

    }
}

public class Task2 {
    public static void main(String[] args) {
        for (int i = 1; i < 10; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(i + "*" + j + "=" + i * j+" ");
            }
            System.out.println();
        }
    }
}

public class Task3 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入一个三位树的整数：");
        int n = input.nextInt();
        boolean flag = isShuiXianHua(n);
        System.out.println(n + (flag ? "是" : "不是") + "水仙花数");

    }

    public static boolean isShuiXianHua(int n) {
        //个位数
        int ge = n % 10;
        //十位数
        int shi = n / 10 % 10;
        //百位数
        int bai = n / 10 / 10 % 10;
        int i = ge * ge * ge + shi * shi * shi + bai * bai * bai;
        return i==n;
    }
}

3-2

public class Task1 {
    public static void main(String[] args) {
        int[][] a = new int[30][5];//存放30个学生的5门成绩
        int[] b = new int[30]; //存放每个学生5门课程的平均成绩
        //输入每个学生的5门成绩
        for (int i = 0; i < a.length; i++) {
            System.out.print("第" + (i + 1) + "个学生的5门成绩:\t");
            int count = 0; //局部变量，学生的成绩
            for (int j = 0; j < a[i].length; j++) {
                a[i][j] = new Random().nextInt(101);//随机生成一个学生一门成绩分数
                count += a[i][j]; //学生5门成绩的总分
                System.out.print(a[i][j] + "\t");
            }
            count = count / 5; //学生5门成绩的平均分
            b[i] = count; //存放到b数组中
            System.out.println("");
            System.out.println("第" + (i + 1) + "个学生的5门成绩的平均分为:\t" + b[i]);
            System.out.println();
        }


        for (int i = 0; i < b.length; i++) {
            System.out.println("第" + (i + 1) + "个学生的5门成绩的平均分为:\t" + b[i]);
        }
    }
}

public class Task2 {
    public static void main(String[] args) {
        int factorial = getFactorial(5);
        System.out.println("5的阶乘：" + factorial);
    }

    public static int getFactorial(int i) {
        int sum = 1;
        if (i < 0)
            throw new IllegalArgumentException("必须为正整数!");
        if (i == 1) {
            return 1;
        } else {
            return i * getFactorial(i - 1);
        }
    }
}

3-3

public class Task1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int count = 0;
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            if (i % 7 == 0) {
                count++;
                sum += i;
            }
        }
        System.out.println("1~" + n + "之间能被 7 整除的整数的个数：" + count);
        System.out.println("被 7 整 除的数的和：" +sum);

    }
}

public class Task2 {
    public static void main(String[] args) {
        int n = new Scanner(System.in).nextInt();
        for (int i = 2; i <= n; i++) {
            boolean flag = true;
            for (int j = 2; j < i; j++) {
                if (0 == i % j) {
                    flag = false;
                    break;
                }
            }
            if (flag) {
                System.out.print(i + " ");
            }
        }
    }

}

public class Task3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("输入一个整数:");
        int number = in.nextInt();
        for (int i = 1; i <= number * 2 - 1; i++) {
            //上半部分
            if (i <= number) {
                for (int j = number; j > i; j--) {
                    System.out.print(" ");
                }
                for (int x = 1; x <= i * 2 - 1; x++) {
                    System.out.print("*");
                }
                //下半部分
            } else {
                for (int j = 1; j <= i - number; j++) {
                    System.out.print(" ");
                }
                for (int x = number * 2 - 2; x > (i - number) * 2 - 1; x--) {
                    System.out.print("*");
                }
            }
            System.out.println();
        }
    }
}

3-4

public class Task1 {
    public static void main(String[] args) {
        int count = 4 * 2;
        for (int j = 0; j <= count; j += 2) {
            //i=列的最大个数
            for (int i = 7; i > j; i--) {
                System.out.print("*");
            }
            System.out.println("");
        }

    }
}

public class Task2 {
    public static void main(String[] args) {
        int[] arr = new int[10];
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入十个数：");
        for (int i = 0; i < 10; i++) {
            arr[i]=scanner.nextInt();
        }
        int max=0;
        for (int i = 0; i < 10; i++) {
            if (max<arr[i]){
                max=arr[i];
            }
        }
        System.out.println("最大值为："+max);
    }
}

public class Task3 {
    public static void main(String[] args) {
        int n =new Scanner(System.in).nextInt();
        int result = getResult(n);
        System.out.println("结果："+result);
    }

    public static int getResult(int n) {
        int length = Integer.toString(n).length();
        int p = 1;//获取的位数
        int m = 10;//取余
        int num = 1;//存储数字各个位数的乘积
        for (int i = 1; i <= length; i++) {
            int g = n / p % m;
            p *= 10;
            num *= g;
        }
        return num;
    }
}

3-5

public class Task2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入定价：");
        float price = scanner.nextFloat();
        System.out.println("输入您要购买的数量：");
        int n = scanner.nextInt();

        double discount;
        if (n > 100) {
            discount = 0.8;
        } else if (n > 10) {
            discount = 0.85;
        } else {
            discount = 0.9;
        }
        System.out.println("您购买" + n + "本价格" + price + "的总价：" + n * discount * price);


    }
}

public class Task2 {
    public static void main(String[] args) {
        String str = " ";
        int sum = 0;
        for (int i = 100; i <= 200; i++) {
            if (i % 10 == i / 100) {
                sum += i;
                System.out.print(i + " ");
            }
        }
        System.out.println("\n100—200 的范围内所有回文数的和为:" + sum);

    }
}

3-9

public class Task1 {
    public static void main(String[] args) {
        int i = new Scanner(System.in).nextInt();
        if (i > 100) {
            System.out.println("Score is error!");
        } else if (i >= 90) {
            System.out.println("A");
        } else if (i >= 80) {
            System.out.println("B");
        } else if (i >= 70) {
            System.out.println("C");
        } else if (i >= 60) {
            System.out.println("D");
        } else if (i >= 0) {
            System.out.println("E");
        } else {
            System.out.println("Score is error!");
        }
    }
}

public class Task2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            double n = sc.nextInt();
            double m = sc.nextInt();
            double sum = 0;
            for (int i = 0; i < m; i++) {
                sum += n;
                n = Math.sqrt(n);
            }
            System.out.printf("%.2f\n", sum);
        }
    }
}

public class Task3 {
   public static void main(String[] args) {
      Scanner reader = new Scanner(System.in);
      int t;
      double sum;
      t = reader.nextInt();
      while(t > 0) {
         int n = reader.nextInt();
         int flag = 1;
         sum = 0;
         if(n >= 300)
            n = 300;
         for(int i = 1; i <= n; i++) {
            sum += (flag * 1.0)/ i;
            flag = -flag;
         }
         t--;
         System.out.printf("%.2f\n", sum);
      }
      reader.close();
   }
}

3-10

public class Task1 {
    public static void main(String[] args) {
        double arr[] = {9.8, 12, 45, 67, 23, 1.98, 2.55, 45};
        double max = 0;
        double min = 100;
        double sum = 0;
        for (double v : arr) {
            if (v > max) {
                max = v;
            }
            if (v < min) {
                min = v;
            }
            sum+=v;
        }
        System.out.println("{9.8, 12, 45, 67, 23, 1.98, 2.55, 45}中最大值为："+max);
        System.out.println("{9.8, 12, 45, 67, 23, 1.98, 2.55, 45}中最小值为："+min);
        System.out.println("{9.8, 12, 45, 67, 23, 1.98, 2.55, 45}的平均值为："+sum/arr.length);
    }
}

public class Task2 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入一个2~10的正整数：");
        int n = input.nextInt();
        int sum = 1;
        for (int i = 1; i <= n; i++) {
            sum += Integer.parseInt("2" + i);
        }
        System.out.println(sum);
    }
}

public class Task3 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入你的工资：");
        double i = sc.nextDouble();

        System.out.println("你要交的税为：" + IsMoney(i));
    }

    public static double IsMoney(double money) {
        double i = money;
        double s = i - 3000;
        double j = 0;
        double M = 1500 * 0.05;// 一级税额
        if (s > 0) {
            if (s <= 1500) {
                j = s * 0.05;
            } else if (s <= 4500) {
                j = M + (s - 1500) * 0.1;
            } else if (s <= 9000) {
                j = M + 3000 * 0.1 + (s - 4500) * 0.2;
            } else if (s <= 35000) {
                j = M + 3000 * 0.1 + 4500 * 0.2 + (s - 9000) * 0.25;
            } else if (s <= 55000) {
                j = M + 3000 * 0.1 + 4500 * 0.2 + 26000 * 0.25 + (s - 35000)
                        * 0.3;
            } else if (s <= 80000) {
                j = M + 3000 * 0.1 + 4500 * 0.2 + 26000 * 0.25 + 20000 * 0.3
                        + (s - 55000) * 0.35;
            } else {
                j = M + 3000 * 0.1 + 4500 * 0.2 + 26000 * 0.25 + 20000 * 0.3
                        + 25000 * 0.35 + (s - 80000) * 0.45;
            }
            return j;
        } else {
            System.out.println("不交税！");
        }
        return 0;
    }
}

3-15

public class Task1 {
    public static void main(String[] args) {
        int num = 0;//计算累加
        for (int i = 1; i <= 10000; i++) { //一一尝试10000以内的数字
            for (int j = 1; j < i; j++) { //验证对应的i是不是完全数
                if (i % j == 0) {
                    num += j;//如果j是这个i的因子就把j加到num里面
                }
            }
            if (i == num) {
                System.out.println("数字 " + i + " 是完全数..");
            }
            num = 0;//清零
        }
    }
}

public class Task2 {
    public static void main(String[] args) {
        int total = 0;
        for (int i = 0; i <= 20; i++) {
            for (int j = 0; j <= 50; j++) {
                for (int k = 0; k <= 100; k++) {
                    if (5 * i + 2 * j + k == 100)
                        total++;
                }
            }
        }
        System.out.println("将一元钱换成5分，2分和1分的硬币,兑换的方法数一共有" + total + "种");
    }
}

public class Task3 {
    public static void main(String[] args) {
        Square square = new Square();
        Circle circle = new Circle();
        double area = square.area(2);
        double area1 = circle.area(3);
        System.out.println("边长为2的正方形面积" + area);
        System.out.println("半径为3的圆形面积为：" + area1);
    }
}

interface Shape {
    abstract double area(double n);
}

class Square implements Shape {

    @Override
    public double area(double n) {
        return n * n;
    }
}

class Circle implements Shape {

    @Override
    public double area(double n) {
        return 3.14 * n * n;
    }
}

3-16

public class Task1 {
    public static void main(String[] args) {
        int total = 0;
        for (int i = 0; i <= 20; i++) {
            for (int j = 0; j <= 50; j++) {
                for (int k = 0; k <= 100; k++) {
                    if (5 * i + 2 * j + k == 100)
                        total++;
                }
            }
        }
        System.out.println("将一元钱换成5分，2分和1分的硬币,兑换的方法数一共有" + total + "种");
    }
}

public class Task2 {
    public static void main(String[] args) {
        int[] arr = new int[10];
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入十个数：");
        for (int i = 0; i < 10; i++) {
            arr[i] = scanner.nextInt();
        }
        for (int i = arr.length - 1; i >= 0; i--) {
            System.out.print(arr[i] + " ");
        }
    }
}

public class Task3 {
    public static void main(String[] args) {
        //向上转型，把Bird类型转换为Animal类型
        Animal animal = new Bird();
        animal.eat();
        Bird bird = (Bird) animal;
        // 向下转型，把Animal类型转换为Bird类型
        bird.fly();
    }
}

class Animal {
    public void eat() {
        System.out.println("吃东西");
    }
}

interface A {
    abstract void fly();
}

class Bird extends Animal implements A {
    @Override
    public void eat() {
        System.out.println("鸟儿吃虫");
    }

    @Override
    public void fly() {
        System.out.println("鸟儿飞翔");
    }
}

3-17

//输出斐波那契数列
public class Task1 {
    public static void main(String[] args) {
        int a = 1;
        int b = 1;
        for(int i = 1;i <= 20;i++) {
            System.out.print(a + "\t" + b + "\t");
            a = a + b;
            b = a + b;
        }

    }
}

//有一条长阶梯，若每步跨2阶，则最后剩余1阶，若每步跨3阶，则最后剩2阶，若每步跨5阶，则最后剩4阶，若每步跨6阶则最后剩5阶，若每步跨7阶，最后才正好一阶不剩。请问,这条阶梯共有多少阶?
public class Task2 {
    public static void main(String[] args) {
        for (int i = 1; ; i++) {
            if (i % 2 == 1 &&
                    i % 3 == 2 &&
                    i % 5 == 4 &&
                    i % 6 == 5 &&
                    i % 7 == 0) {
                System.out.println(i);
                break;
            }
        }
    }
}

public class Task3 {
    public static void main(String[] args) {
        Student student = new Student("阿红",10,2002222);
        Worker worker = new Worker("阿清",30,1988888);
        System.out.println("学号："+student.getStuId()+",姓名："+student.getName()+",年龄："+student.getAge());
        student.study();
        student.eat();
        System.out.println("工号："+worker.getWorkId()+",姓名："+worker.getName()+",年龄："+worker.getAge());
        worker.work();
        worker.eat();
    }
}

abstract class Person {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    abstract public void eat();
}

class Student extends Person {
    private int stuId;

    public int getStuId() {
        return stuId;
    }

    public void setStuId(int stuId) {
        this.stuId = stuId;
    }

    public Student(String name, int age, int stuId) {
        super(name, age);
        this.stuId = stuId;
    }

    @Override
    public void eat() {
        System.out.println("学生在食堂吃饭");
    }

    public void study() {
        System.out.println("我爱学习");
    }
}

class Worker extends Person {
    private int workId;

    public int getWorkId() {
        return workId;
    }

    public void setWorkId(int workId) {
        this.workId = workId;
    }

    public Worker(String name, int age, int workId) {
        super(name, age);
        this.workId = workId;
    }

    @Override
    public void eat() {
        System.out.println("工人在工厂食堂吃饭");
    }

    public void work() {
        System.out.println("我爱工作");
    }

}

--------Before--------

3_11

public class Task1 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入一个月份:");
        int month = scan.nextInt();
        switch (month) {
            case 12:
            case 1:
            case 2:
                System.out.print("您输入的月份属于冬季。");
                break;
            case 3:
            case 4:
            case 5:
                System.out.print("您输入的月份属于春季");
                break;
            case 6:
            case 7:
            case 8:
                System.out.print("您输入的月份属于夏季");
                break;
            case 9:
            case 10:
            case 11:
                System.out.print("您输入的月份属于秋季");
                break;
            default:
                System.out.print("您输入的月份：" + month + " 未在1~12范围内!");
        }
    }
}

public class Task2 {
    public static void main(String[] args) {
        int year = 2017;
        for (double i = 0.85; i < 10; year++) {
            i = i * (1 + 0.32);
        }
        System.out.println("店铺盈利到10万元需要：" + year + " 年");
    }

}

public class Task3 {
    public static void main(String[] args) {
        Circle circle = new Circle(10);
        System.out.println("半径10cm的圆面积为：" + circle.mianJI() + " 周长：" + circle.zhouChang());
        Rect rect = new Rect(10, 6);
        System.out.println("长10cm、宽6cm的矩形面积为：" + rect.mianJI() + " 周长：" + rect.zhouChang());


    }
}

abstract class Shape {
    abstract double mianJI();

    abstract double zhouChang();
}

class Circle extends Shape {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    @Override
    double mianJI() {
        return Math.PI * radius * radius;
    }

    @Override
    double zhouChang() {
        return 2 * Math.PI * radius;
    }
}

class Rect extends Shape {
    private double length;
    private double height;

    public Rect(double length, double height) {
        this.length = length;
        this.height = height;
    }

    @Override
    double mianJI() {
        return length * height;
    }

    @Override
    double zhouChang() {
        return 2 * (length + height);
    }
}

3_12

public class Task1 {
    public static void main(String[] args) {
        int n = 10;
        int arr[] = new int[n];
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入十个数，空格隔开");
        for (int i = 0; i < 10; i++) {
            arr[i] = scanner.nextInt();
        }
        System.out.println("待排序列：" + Arrays.toString(arr));
        for (int i = 0; i < n - 1; i++) {
            boolean flag = false;
            for (int j = n - 1; j > i; j--) {
                if (arr[j - 1] > arr[j]) {
                    int tmp = arr[j - 1];
                    arr[j - 1] = arr[j];
                    arr[j] = tmp;
                    flag = true;
                }
            }
        }
        System.out.println("已排序列：" + Arrays.toString(arr));
    }
}

public class Task2 {
    public static void main(String[] args) {
        int sum = 0, i = 1;
        while (i <= 200) {
            if (i % 3 == 0) {
                sum += i;
            }
            i++;
        }
        System.out.println("1~200之间3倍数之和："+sum);
    }
}

public class Task3 {
    public static void main(String[] args) {
        Person person = new Person("zhangsan", 18);
        person.show();
        Student student = new Student("lisi", 20, "qinghai");
        student.show();
    }
}

class Person {
    public String name;
    public int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public void show() {
        System.out.println("姓名：" + this.name + " 年龄：" + this.age);
    }
}

class Student extends Person {

    private String school;

    public Student(String name, int age, String school) {
        super(name, age);
        this.school = school;
    }


    public void show() {
        System.out.println("姓名：" + this.name + " 年龄：" + this.age + " 学校：" + this.school);
    }
}

3_13

public class Task1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入消费金额：");
        int money = scanner.nextInt();
        double discount;

        int c = (money < 200 ? 1 : 0)
                + (money < 400 ? 1 : 0)
                + (money < 600 ? 1 : 0)
                + (money < 800 ? 1 : 0)
                + (money < 1000 ? 1 : 0);


        switch (c) {
            case 0:
                discount = 0.5;
                System.out.println("消费在大于1000，享受5折优惠，折后价：" + discount * money);
                break;
            case 1:
                discount = 0.6;
                System.out.println("消费在800~999之间，享受6折优惠，折后价：" + discount * money);

                break;
            case 2:
                discount = 0.7;
                System.out.println("消费在600~799之间，享受7折优惠，折后价：" + discount * money);
                break;
            case 3:
                discount = 0.8;
                System.out.println("消费在400~599之间，享受折8优惠，折后价：" + discount * money);
                break;
            case 4:
                discount = 0.9;
                System.out.println("消费在200~399之间，享受9折优惠，折后价：" + discount * money);
                break;
            case 5:
                System.out.println("消费小于200，无折扣");
                break;
        }
    }
}

public class Task2 {
    public static void main(String[] args) {
        final int max = 1000;
        double item = 0;
        double sum = 0;
        int flag = -1;

        int n = 0;
        for (n = 0; n <= max; n++) {
            flag *= -1;
            item = flag * 1.0 / (2 * n + 1);
            sum += item;
        }
        System.out.println(4 * sum);
    }
}

public class Task3 {
    public static void main(String[] args) {
        Flower flower = new Flower("白色", 10);
        flower.showInfo();
        Rose rose = new Rose("紫色",30,"大理");
        rose.showInfo();
        rose.warn();


    }

}

class Flower {
    private String color;
    private double price;

    public Flower() {
    }

    public Flower(String color, double price) {
        this.color = color;
        this.price = price;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public void showInfo() {
        System.out.println("花的颜色是" + this.color+"，价格是 " + this.price +"元");
    }
}

class Rose extends Flower {
    private String origin;

    public Rose(String color, double price, String origin) {
        super(color, price);
        this.origin = origin;
    }

    public String getOrigin() {
        return origin;
    }

    public void setOrigin(String origin) {
        this.origin = origin;
    }

    @Override
    public void showInfo() {
        super.showInfo();
        System.out.println("产地是" + this.origin);
    }

    public void warn(){
        System.out.println("不要摘玫瑰花，小心扎手！");
    }
}

3_14

public class Task1 {
    public static void main(String[] args) {
        double money = 0;
        for (int i = 0; i < 5; i++) {
            money = (money + 1000) / (1 + 12 * 0.0063);
        }
        System.out.println("存钱时应存入:" + money);
    }
}

public class Task2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入一个0~99999 之间的任意数");
        int number = sc.nextInt();
        if (number / 10000 >= 1 && number / 10000 < 10) {
            System.out.println(number + " 是5位数");
        } else if (number / 1000 >= 1) {
            System.out.println(number + " 是4位数");
        } else if (number / 100 >= 1) {
            System.out.println(number + " 是3位数");
        } else if (number / 10 >= 1) {
            System.out.println(number + " 是2位数");
        } else if (number >= 1) {
            System.out.println(number + " 是1位数");
        }
    }

}

public class Task3 {
    public static void main(String[] args) {
        SportsCar car1 = new SportsCar("宝马");
        car1.run();
        car1.price();

    }
}
abstract class Car{
    private String brand;

    public Car(String brand) {
        this.brand = brand;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    abstract void run();
}
class SportsCar extends Car{

    public SportsCar(String brand) {
        super(brand);
    }

    @Override
    void run() {
        System.out.println("超级跑车");
    }
     public void price(){
         System.out.println("售价100w");
     }
}