第五周作业

1. 打印出所有的"水仙花数"，所谓"水仙花数"是指一个三位数，其各位数字立方和等于该数本身。例如：153是一个"水仙花数"，因为153=1的三次方＋5的三次方＋3的三次方。（知识点：循环语句、条件语句

import java.util.Scanner;

public class nn {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for(int a=100;a<1000;a++) {
            int gw=a%10;
            int sw=a/10%10;
            int bw=a/100;
            if(gw*gw*gw+sw*sw*sw+bw*bw*bw==a) {
                System.out.println(a);
            }
        }
    }
}

2.在控制台输出以下图形（知识点：循环语句、条件语句）

import java.util.Scanner;

public class nn {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         for(int a = 1;a <= 6;a++)
            {
                for(int i = 1;i <= a;i++)
                    System.out.printf("%d ",i);
                System.out.print("
");
            }
            System.out.print("
");
             
            for(int a = 6;a >= 1;a--)
            {
                for(int i = 1;i <= a;i++)
                    System.out.printf("%d ",i);
                System.out.print("
");
            }
            System.out.print("
");
             
            for(int a = 1;a <= 6;a++)
            {  
                for(int i = 1;i <= 2 * (6 - a);i++)
                    System.out.print(" ");
                 
                for(int i = a;i >= 1;i--)
                    System.out.printf("%d ",i);
                System.out.print("
");
            }
            System.out.print("
");
             
            for(int a = 6;a >= 1;a--)
            {
                for(int i = 1;i <= 2 *(6-a);i++)
                    System.out.print(" ");
                for(int i = 1;i <= a;i++)
                    System.out.printf("%d ",i);
                System.out.print("
");
            }
    }
}

3. 输入年月日，判断这是这一年中的第几天（知识点：循环语句、条件语句）

import java.util.Scanner;

public class nn {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int x = 0;
            Scanner sc=new Scanner(System.in);
            System.out.print("请输入年份");
            int year=sc.nextInt();
            System.out.print("请输入月份");
            int month=sc.nextInt();
            System.out.print("请输入日期");
            int date= sc.nextInt();
            if(year%4==0 && year%100!=0 || year%400==0) {
                switch(month) {
                case 1:  x=31; break;
                case 2:  x=31+29;break;
                case 3:  x=31+29+31;break;
                case 4:  x=31+29+31+30;break;
                case 5:  x=31+29+31+30+31;break;
                case 6:  x=31+29+31+30+31+30;break;
                case 7:  x=31+29+31+30+31+30+31;break;
                case 8:  x=31+29+31+30+31+30+31+31;break;
                case 9:  x=31+29+31+30+31+30+31+31+30;break;
                case 10: x=31+29+31+30+31+30+31+31+30+31;break;
                case 11: x=31+29+31+30+31+30+31+31+30+31+30;break;
                case 12: x=31+29+31+30+31+30+31+31+30+31+30+31;break;
                }
            }else {
                switch(month) {
                case 1:  x=31;break;
                case 2:  x=31+28;break;
                case 3:  x=31+28+31;break;
                case 4:  x=31+28+31+30;break;
                case 5:  x=31+28+31+30+31;break;
                case 6:  x=31+28+31+30+31+30;break;
                case 7:  x=31+28+31+30+31+30+31;break;
                case 8:  x=31+28+31+30+31+30+31+31;break;
                case 9:  x=31+28+31+30+31+30+31+31+30;break;
                case 10: x=31+28+31+30+31+30+31+31+30+31;break;
                case 11: x=31+28+31+30+31+30+31+31+30+31+30;break;
                case 12: x=31+28+31+30+31+30+31+31+30+31+30+31;break;
                }
            }
            System.out.println(year+"年"+month+"月"+date+"日"+"是第"+(x+date)+"天");
    }
}

4．由控制台输入一个4位整数，求将该数反转以后的数，如原数为1234，反转后的数位4321（知识点：循环语句、条件语句）

import java.util.Scanner;

public class nn {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入一个四位数");
        int num=sc.nextInt();
        int qian=num/1000;
        int bai=num/100%10;
        int shi=num/10%10;
        int ge=num%10;
        System.out.println("原先的数为："+num+"现在的为"+(qian+bai*10+shi*100+ge*1000));
    }
}