tmp.java

package com.school;


import java.util.Scanner;


interface Task {
    public String getName();

    public void run();

}

class Task1 implements Task {

    @Override
    public String getName() {
        return "Task 1 水仙花数";
    }

    @Override
    public void run() {
        for (int i = 100; i < 999; i++) {
            int a = i / 100 % 100, b = i / 10 % 10, c = i % 10;
            int sum = (int) (Math.pow(a, 3) + Math.pow(b, 3) + Math.pow(c, 3));

//            System.out.println("a = " + a);
//            System.out.println("b = " + b);
//            System.out.println("c = " + c);
//            System.out.println("sum = " + sum);

            if (sum == i) System.out.println(i);


        }
        System.out.println(" ");
    }
}


class Task2 implements Task {

    private int getFib(int n) {
        if (n < 0) {
            return -1;
        } else if (n == 0 || n == 1) {
            return 1;
        } else {
            return getFib(n - 1) + getFib(n - 2);
        }
    }

    @Override
    public String getName() {
        return "Task 2 兔子总数";
    }

    private void method1(int monthToShow) {
        long firstMonth = 0, secondMonth = 1, birthMonth = 0;
        for (int i = 0; i < monthToShow; i++) {
            if (i < 2) System.out.printf("第 %d 月, 一共有 %d 只兔子\n", i + 1, firstMonth);
            else {
                birthMonth += secondMonth;
                secondMonth = firstMonth;
                firstMonth = birthMonth;

                System.out.printf("第 %d 月, 一共有 %d 只兔子\n", i + 1, firstMonth + secondMonth + birthMonth);
            }
        }

    }

    private void method2(int monthToShow) {
        for (int i = 0; i < monthToShow; i++) {
            System.out.printf("第 %d 月, 一共有 %d 只兔子\n", i + 1, this.getFib(i));
        }

    }

    @Override
    public void run() {
        {
            Scanner sc = new Scanner(System.in);

            System.out.print("遍历多少个月数: ");
            int monthToShow = sc.nextInt();

//            this.method1(monthToShow);
            this.method2(monthToShow);

        }
    }
}

class Task3 implements Task {

    @Override
    public String getName() {
        return "Task 3 素数判断";
    }

    private boolean isPrime(int in) {

        for (int i = 2; i < in; i++) {
            //若能除尽，则不为质数
            if ((in % i) == 0) {
                return false;
            }
        }

        return true;
    }

    @Override
    public void run() {
        for (int i = 101; i < 200; i++) {
            if (this.isPrime(i)) System.out.println(i);
        }
    }
}

class Task4 implements Task {

    @Override
    public String getName() {
        return "Task 4 正整数分解质因数";
    }

    private String resolvePrime(int target) {
        StringBuilder stringBuilder = new StringBuilder(target + " = ");

        int minimumPrime = 2;

        // 辗转相除法
        while (minimumPrime <= target) {

            if (target % minimumPrime == 0) {
                stringBuilder.append(minimumPrime).append(" * ");

                target /= minimumPrime;
                minimumPrime = 2;
            } else {
                minimumPrime++;
            }
        }


        stringBuilder.setLength(stringBuilder.length() - 3);
        return stringBuilder.toString();
    }

    @Override
    public void run() {
        Scanner sc = new Scanner(System.in);

        System.out.print("分解质因数: ");
        int nextInt = sc.nextInt();

//            this.method1(monthToShow);
        System.out.println(
                this.resolvePrime(nextInt)
        );
    }
}

class Task5 implements Task {

    @Override
    public String getName() {
        return "Task 5 条件运算符";
    }

    @Override
    public void run() {
        Scanner sc = new Scanner(System.in);

        System.out.print("输入学习成绩: ");
        int nextInt = sc.nextInt();

        System.out.println(nextInt < 60 ? 'C' : nextInt < 89 ? 'B' : 'A');
    }
}

class Task6 implements Task {
    private int a, b;

    @Override
    public String getName() {
        return "Task 6";
    }

    private int maxCommonDivisor() {
        int m = a, n = b;


        if (m < n) {

            int temp = m;
            m = n;
            n = temp;
        }
        while (m % n != 0) {
            int temp = m % n;
            m = n;
            n = temp;
        }
        return n;
    }

    private int minCommonMultiple() {
        return a * b / maxCommonDivisor();
    }

    @Override
    public void run() {
        Scanner sc = new Scanner(System.in);

        System.out.println("请输入两个数: ");

        a = sc.nextInt();
        b = sc.nextInt();

        System.out.printf("最大公约数 %d 最小公倍数 %d\n", maxCommonDivisor(), minCommonMultiple());

    }
}

class Task7 implements Task {

    @Override
    public String getName() {
        return "Task 7 100 内完全数";
    }

    @Override
    public void run() {
        for (int i = 1; i <= 1000; i++) {
            int factor = 0;
            for (int j = 1; j < i / 2 + 1; j++) {
                if (i % j == 0)
                    factor += j;
            }
            if (factor == i)
                System.out.println("  " + i);
        }
    }
}

class Task8 implements Task {

    @Override
    public String getName() {
        return "Task 8 球落地问题";
    }

    @Override
    public void run() {
        final Integer HEIGHT = 100;
        final Integer TIME = 10;
        double now = HEIGHT;
        double past = 0.0;

        for (int i = 0; i < TIME; i++) {
            past += now * 1.5;
            now /= 2;
        }

        System.out.printf("第 %d 次经过 %f 米\n第 %d 次经过反弹 %f 米", TIME, past, TIME, now);
    }
}

public class Main {

    public static void main(String[] args) {
        Task[] tasks = {
                new Task1(),
                new Task2(),
                new Task3(),
                new Task4(),
                new Task5(),
                new Task6(),
                new Task7(),
                new Task8(),
        };

        for (Task task : tasks) {
            System.out.println("========= " + task.getName() + " ==========\n");

            task.run();

            System.out.println(" ");
        }


    }
}