JAVA-1.3-上机

/*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 study;
import java.util.*;
public class homework {
    public static void main(String[] args) {
        for(int i=100;i<1000;i++) {
            int ge=i%10;
            int shi=i/10%10;
            int bai=i/100;
            if(ge*ge*ge+shi*shi*shi+bai*bai*bai==i) {
                System.out.println(i);
            }
        }
    }
    
}

/*2.在控制台输出以下图形（知识点：循环语句、条件语句）
 */
package study;
import java.util.*;
public class homework {
    public static void main(String[] args) {
        for (int i = 1; i < 7; i++) {//1.
            for (int j = 1; j <= i; j++) {
                System.out.print(j);
            }
            System.out.print("\n");
        }
        for (int i = 1; i < 7; i++) {//2.
            for (int j =1 ; j <= (7-i); j++) {
                System.out.print(j);
            }
            System.out.print("\n");
        }
        for (int i = 1; i < 7; i++) {//3.
            for (int j = 1; j <= (7-i); j++) {
                System.out.print(" ");
            }
            for (int j = i; j > 0; j--) {
                System.out.print(j);
            }
            System.out.print("\n");
        }
        for (int i = 1; i < 7; i++) {//4.
            for (int j = (7-i); j <7; j++) {
                System.out.print(" ");
            }
            for (int j = 1; j <= (7-i); j++) {
                System.out.print(j);
            }
            System.out.print("\n");
        }
    }
    
}

/*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 study;
import java.util.*;
public class homework {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入四个数:");
        int num=sc.nextInt();
        int g,s,b,q;
         q = num % 10;
         b = num / 10 % 10;
         s = num / 100 % 10;
         g = num / 1000;
        System.out.println(q*1000+b*100+s*10+g);
    }
    
}

/*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 study;
import java.util.*;
public class homework {
    public static void main(String[] args) {
         Scanner input = new Scanner(System.in);
         System.out.print("year:");
         int year = input.nextInt();
         System.out.print("month:");
         int month = input.nextInt();
         System.out.print("day:");
         int day = input.nextInt();
         int a=0;
         for (int j = 1; j < month; j++) {
             switch(j) {
             case 4:
             case 6:
             case 9:
             case 11:
                 a+=30;
                 break;
             case 2:
                 if(year%400==0||year%4==0&&year%100!=0)
                     a+=29;
                 else
                     a+=28;
              
                 break;
               default:
                    a+=31;
                    break;
           }
           
        }
         a+=day;
         System.out.println("这是第"+a+"天");
    }
    
}