第五周上机练习

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 pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        for (int i = 100; i < 1000; i++) {
            int ge = i % 10;
            int shi = i % 100 / 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 pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        for(int i=1;i<=6;i++){
            for(int j=1;j<=i;j++){
                System.out.print(j);
            }
            System.out.println(); 
        }
    }
}

package pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        for(int i=6;i>=0;i--){
            for(int j=1;j<=i;j++){
                System.out.print(j);
            }
            System.out.println(); 
        }
    }
}

package pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        for(int i=1;i<7;i++) {
            for (int k = 1; k <=6-i ; k++) {
                System.out.print(" ");
            }
            for(int j=i;j>0;j--) {
                System.out.print(j);
            }
            System.out.println();
        }
    }
}

package pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        for(int i = 6;i >= 1;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 pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        int year,month,day,sum=0,eryue=28;
        Scanner in = new Scanner(System.in);
        System.out.print("请输入年份:");
        year = in.nextInt();
        System.out.print("请输入月份:");
        month = in.nextInt();
        System.out.print("请输入几号:");
        day = in.nextInt();
        if((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
        {
            eryue = 29;
        }        
        switch(month)
            {
                    case 1:
                        sum = day;
                        break;
                    case 2:
                        sum = 31 + day;
                        break;
                    case 3:
                        sum = 31+eryue+day;
                        break;
                    case 4:
                        sum = 31+eryue+31+day;
                        break;
                    case 5:
                        sum = 31+eryue+31+30+day;
                        break;
                    case 6:
                        sum = 31+eryue+31+30+31+day;
                        break;
                    case 7:
                        sum = 31+eryue+31+30+31+30+day;
                        break;
                    case 8:
                        sum = 31+eryue+31+30+31+30+31+day;
                        break;
                    case 9:
                        sum = 31+eryue+31+30+31+30+31+31+day;
                        break;
                    case 10:
                        sum = 31+eryue+31+30+31+30+31+31+30+day;
                        break;
                    case 11:
                        sum = 31+eryue+31+30+31+30+31+31+30+31+day;
                        break;
                    case 12:
                        sum = 31+eryue+31+30+31+30+31+31+30+31+30+day;
        }
        System.out.println(year+" 年 "+month+" 月 " + day + "号是当年的第"+sum+"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 pro1;
import java.util.Scanner;
public class test {
    public static void main(String[] args) {
        Scanner aaa = new Scanner(System.in);
        System.out.println("请输入一个数：");
            int x = aaa.nextInt();
            if(x >= 1000 && x < 10000){
                int ge = x % 10;
                int shi = x % 100 / 10;               
                int bai = x % 1000 / 100;
                int qian = x / 1000;
                int sum = qian + bai*10 +shi*100 +ge*1000;
                System.out.println(sum);
            }
     }
}