JAVA基礎——循環結構題目1答案

package test1;

import java.util.Scanner;

public class Test1 {

	public static void main(String[] args) {
		while(true){
			int x=0;
			int y=0;
			while(true){
			Scanner sc=new Scanner(System.in);
		    int a=sc.nextInt();
		    if(a==0)
		    	break;
		    else if(a<0)
		    	x++;
		    else
		    	y++;
			}
		    System.out.println("負數:"+x+"正數："+y);
			
		}	
		
		
	}
}
package test1;

public class Test2 {
	public static void main(String[] args){
		
		for(int i=4;i<100;i=i+4)
			System.out.print(i+"   ");
	}

}
package test1;

import java.util.Scanner;

public class Test3 {

	public static void main(String[] args) {
		while(true){
		System.out.println("請輸入用戶名");
		Scanner sc=new Scanner(System.in);
	    String a=sc.nextLine();
	    System.out.println("請輸入密碼");
		Scanner in=new Scanner(System.in);
	    String b=sc.nextLine();
	    if(a.equals("admin")&&b.equals("111"))
	    {
	    	System.out.println("登陸成功");
	    	break;
	    }
	    else
	    	System.out.println("用戶名或密碼不正確，請重新輸入！！！");
		}
	}
	
}
package test1;

public class Test4 {

	public static void main(String[] args) {
		for(int i=1900;i<=2050;i++)
			if((i%4==0 && i%100!=0)||i%400==0)
				System.out.print(i+"  ");
		
	}
}
package test1;

import java.util.Scanner;

public class Test5 {

	
	public static void main(String[] args) {
		while(true){
		System.out.println("***********************");
		System.out.println("1.管理員           2.顧客         3.退出");
		System.out.println("***********************");
		System.out.println("請輸入數字選擇登陸");
		Scanner sc=new Scanner(System.in);
		int i=sc.nextInt();
		switch(i){
		case 1:
			System.out.println("管理員登錄過程省略");
			break;
		case 2:
			System.out.println("顧客登錄過程省略");
			break;
		default:
				System.out.println("系統退出");
				break;	
			}
		if(i==3)
			break;
	
	}
	}
}
package test1;

import java.util.Scanner;

public class Test6 {
	public static void main(String[] args) {
		while(true){
		System.out.println("1.矩形      2.三角形   3.圓  4.退出");
		System.out.println("請選擇圖形:");
		Scanner input=new Scanner(System.in);
		int choose=input.nextInt();
		if (choose==1){
			System.out.print("請輸入矩形的寬:");
			Scanner A=new Scanner(System.in);
			int a=A.nextInt();
			System.out.print("請輸入矩形的高:");
			Scanner B=new Scanner(System.in);
			int b=B.nextInt();
			System.out.println("該矩形的面積爲："+a*b);	
		}else if(choose==2){
			System.out.print("請輸入三角形的底:");
			Scanner A=new Scanner(System.in);
			int a=A.nextInt();
			System.out.print("請輸入三角形的的高:");
			Scanner B=new Scanner(System.in);
			int b=B.nextInt();
			System.out.println("該三角形的面積爲："+0.5*a*b);
		}else if(choose==3){
			System.out.print("請輸入圓的半徑:");
			Scanner A=new Scanner(System.in);
			int a=A.nextInt();
			System.out.println("該圓的面積爲："+3.14*a*a);
		}
		else
			break;
	}
	}

}
package test1;

import java.util.Scanner;

public class Test7 {
	public static void main(String[] args) {
		int b=0;
	
	while(true){
		Scanner sc=new Scanner(System.in);
		String in=sc.nextLine();
		if(in.equals("end"))
		{
			System.out.println(b);
			break;
		}
		int a=Integer.parseInt(in);
		if(a>b)
		   b=a;
		
	}
	}
}
package test1;

import java.util.Scanner;

public class Test8 {

	public static void main(String[] args) {
	
			for(int i=100;i<1000;i++)
			{
				int a=i/100;
				int b=(i-100*a)/10;
				int c=i%10;
				if(i==a*a*a+b*b*b+c*c*c)

					System.out.println(i);
			}
		
	}
}
package test1;

public class Test9 {

	public static void main(String[] args) {
		int a=1;
		for(int i=10;i>1;i--)
		    a=(a+1)*2;
		System.out.println(a);
	}
}
package test1;

import java.util.Scanner;

public class Test10 {

	public static void main(String[] args) {
		while(true){
			int i=0;
			Scanner sc=new Scanner(System.in);
			int a=sc.nextInt();
		    String b=Integer.toBinaryString(a);
		    char[]c=b.toCharArray();
		    for(char cc:c)
		    {
		    //	System.out.print(cc);
		    	if (cc==49)
		    		i++;
		    }
		    	System.out.println(i);
		    
		}
		
	}
}
package test1;

import java.util.Scanner;

public class Test11 {

	public static void main(String[] args) {
		while(true){
			System.out.println("請輸入一個數");
			Scanner sc=new Scanner(System.in);
			int a=sc.nextInt();
			for (int i = 2; i<=a; i++) {//外層循環自然數
				for (int j = 2; j < i; j++) {//判斷是否是質數
					if (i%j==0) {
						break;
					}
				}
					if (a%i==0) {//判斷當前質數是否是因子
						a=a/i;
				     System.out.println(i+"   ");
				     i=1;//找出一個質數後還要從最小的質數找
					}
				
				}
				
			}
		}
	}

package test1;

import java.util.Scanner;

public class Test12 {

	public static void main(String[] args) {
	while(true){
		System.out.println("依次輸入兩個數：");
		Scanner sc=new Scanner(System.in);
		int a=sc.nextInt();
		int b=sc.nextInt();
		int c=Math.min(a, b);
		int d=a*b;
		for (int i = 2; i <=c; i++) {
			if(a%i==0 &&b%i==0){//找公因式
				d=d/i;
				c=c/i;
				a=a/i;
				b=b/i;
				i=1;
			}
			
		}
		System.out.println(d);
	}
	}
}