第六次作业

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）

package jjjj;

public class kkkkk {
    public static void main(String[] args) {
        int a,ge,shi,bai;
        System.out.println("所有的水仙花数:
");
        for(a=100;a<1000;a++){
            ge=a%10;
            shi=a/10%10;
            bai=a/100;
            if(ge*ge*ge+shi*shi*shi+bai*bai*bai==a)
                System.out.println(a);
        }
    }
    }

2.

package jjjj;

public class hhhhhhh {

    public static void main(String[] args) {
        for(int i=1;i<7;i++) {
            for(int j=1;j<=i;j++) {
                System.out.print(j);
            }
            System.out.println();
        }
    }

    }

package jjjj;

public class hhhhhhh {
    public static void main(String[] args) {
        for(int i=1;i<7;i++) {
            for(int j=1;j<=7-i;j++) {
                System.out.print(j);
            }
            System.out.println();
        }
    }
}

package jjjj;

public class hhhhhhh{
    public static void main(String[] args) {
        for(int i=1;i<7;i++) {
            for(int j=i;j>0;j--) {
                System.out.print(j);
            }
            System.out.println();
        }
    }
}

package jjjj;

public class hhhhhhh{
    public static void main(String[] args) {
        for(int i=6;i>0;i--) {
            for(int k=0;k<6-i;k++) {
                System.out.print(" ");
            }
            for(int j=1;j<=i;j++) {
                System.out.print(j);
            }
            System.out.println("");
        }
    }
}

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）

package jjjj;

import java.util.Scanner;

public class hhhhhhh {

    public static void main(String[] args) {
        int year;
        int mouth;
        int day = 0;
        int days;
        int d = 0; // 累计天数
        int e = 0;
        Scanner scanner = new Scanner(System.in);
        
        //判断输入的年份和月份和日期是否错误
        do {
            System.out.println("输入年:");
            year = scanner.nextInt();
            System.out.println("输入月:");
            mouth = scanner.nextInt();
            System.out.println("输入日:");
            days = scanner.nextInt();
            if (year < 0 || mouth < 0 || mouth > 12 || days < 0 || days > 31) {
                System.out.println("input error!");
                e = 1;
            }
        } while (e == 1);
        
        for (int i = 1; i < mouth; i++) {
            switch (i) {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12: {
                day = 31;
                break;
            }
            case 4:
            case 6:
            case 9:
            case 11: {
                day = 30;
                break;
            }
            case 2: {
                if ((year % 100 != 0 && year % 4 == 0) || (year % 100 == 0 && year % 400 == 0)) {
                    day = 29;
                } else {
                    day = 28;
                }
            }
            default:
                break;
            }
            d += day;
        }
        System.out.println("这是" + year + "年的" + (d + days) + "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）

package jjjj;

import java.util.Scanner;

public class hhhhhhh {

    public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
           int x = scanner.nextInt();
           if(x>999 && x<=9999){
               int gewei = x%10;
               int shiwei = x % 100 / 10;
               int baiwei = x%1000/100;
               int qianwei = x/1000;
               int sum = qianwei + baiwei*10 +shiwei*100 +gewei*1000;
               System.out.println(sum);
           }
           else{
               System.out.println("error");
           }
    }
}