练习四

1.输入一个年份,判断是不是闰年(能被4整除但不能被100整除,或者能被400整除)
package text;

public class Jiejue4 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(panduan(2000));
        
    }
        public static boolean panduan(int n) {
        if((n%4==0&&n%100!=0)||n%400==0) {
            return true;
        }
        return false;
        }
    }

2.输入一个4位会员卡号,如果百位数字是3的倍数,就输出是幸运会员,否则就输出不是. 
package text;
import java.util.Scanner;
public class Jiejue4 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        
         
            Scanner   input   =    new   Scanner(System.in);
            System.out.println("请输入四位会员卡号");
            int    number=   input.nextInt();
            
            int a= number/100%10;
               
            for( a=0;a<10;a++) {

                if(a%3==0) {
                    
            System.out.println("幸运会员");
            }
            
        
            else
            System.out.println("继续加油");
            }

    
  
}
}

 

3.已知函数,输入x的值,输出对应的y的值. x + 3 ( x > 0 ) y = 0 ( x = 0 ) x2 –1 ( x < 0 )
package apple;
import java.util.*;
public class Main {
            
            
                public static void main(String[] args)
                {
                    Scanner input=new Scanner(System.in);
                    int x=input.nextInt();
                    int y;
                    if(x>0)
                    {
                        y=x+3;
                    }
                    else {
                    if (x<0) 
                    {
                        y=(2*x)-1;
                    }
                    else 
                        y=0;
                    }
}
                    System.out.println(y);
                    
                

 

4.输入三个数,判断能否构成三角形(任意两边之和大于第三边)
package apple;
import java.util.Scanner;
public class Main {
    private double a;
    private double b;
    private double c;

    public void Trigon(double a, double b, double c) {
    this.a = a;
    this.b = b;
    this.c = c;
    }

    public static void main(String[] args) {

    Scanner scan = new Scanner(System.in);
    System.out.println("Please input first side:");//输入第1条边
    double a = scan.nextDouble();
    System.out.println("Please input second side:");//输入第2条边
    double b = scan.nextDouble();
    System.out.println("Please input third side:");////输入第3条边
    double c = scan.nextDouble();
    scan.close();

    Main.isTrigon(a, b, c);//判断输入的能否构成三角形以及类型
    }

    public static void isTrigon(double a, double b, double c) {

    

if(a <= 0 || b <=0 || c <= 0){//如果有小于0的边长，显然不行
    System.out.println("Can't");
    return;
    }

    if (a + b > c && a + c > b && b + c > a) {//2边之和一定要大于第三边
    if (a == b || a == c || b == c) {//等腰
    if (a == b && b == c) {//等边
    System.out.println("可以组成等边三角形");
    } else {
    System.out.println("可以组成等腰三角形");
    }
    return;
    }

    System.out.println("可以组成普通三角形");//普通
    return;
    }

    System.out.println("不能够组成三角形!");//不能构成三角形
    }

    }