자바 프로그래밍 Chapter03 실습문제

2. 

 
public class _02 {
    public static void main(String[] args) {
        int n[][] = { {1}, {1,2,3}, {1}, {1,2,3,4}, {1,2}};
        
        for(int i=0;i<n.length;i++)
        {
            for(int j=0;j<n[i].length;j++)
            {
                System.out.print(n[i][j]+"\t");
            }
            System.out.println();
        }
        
        
    }
}
 

3.

import java.util.Scanner;
public class _03 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        System.out.print("정수를 입력하시오>>");
        int n = scanner.nextInt();
        for(int i=0;i<n;i++)
        {
            for(int j=i;j<n;j++)
            {
                System.out.print("*");
            }
            System.out.println();
        }
        scanner.close();
    }
}
 

4.

import java.util.Scanner;
public class _04 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("소문자 알파벳 하나를 입력하시오>>");
        String s = scanner.next();
        
        char c = s.charAt(0);
        int iNum=(int)c-'a';
        
        for(int i=iNum;i>=0;i--)
        {
            for(int j=0;j<=i;j++)
                System.out.print((char)('a'+j));
            System.out.println();
        }
        scanner.close();
    }
}
 

5.

import java.util.Scanner;
public class _05 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a[] = new int[10];
        System.out.print("양의 정수 10개를 입력하시오>>");
        for(int i=0;i<a.length;i++)
        {
            a[i]=scanner.nextInt();
        }
        System.out.print("3의 배수는 ");
        
        for(int i=0;i<a.length;i++)
        {
            if(a[i]%3==0)
            {
                System.out.print(a[i]+" ");
            }
        }
        scanner.close();
        
 
        
    }
}
 

6. 

import java.util.Scanner;
public class _06 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int [] unit = {50000, 10000, 1000, 500, 100, 50, 10, 1};
        int [] a = new int[8];
        System.out.print("금액을 입력하시오>>");
        int m = scanner.nextInt();
        
        for(int i=0;i<unit.length;i++)
        {
            a[i]=m/unit[i];
            m=m%unit[i];
        }
        for(int i=0;i<unit.length;i++)
        {
            System.out.println(unit[i]+"원 짜리 : "+a[i]+"개");
        }
        scanner.close();
    }
}

7.

import java.util.Random;
public class _07 {
    public static void main(String[] args) {
        int a [] = new int[10];
        double sum=0;
        System.out.print("랜덤한 정수들 : ");
        for(int j=0;j<10;j++)
        {
            int i = (int)(Math.random()*10+1);
            System.out.print(i+" ");
            a[j]=i;
            sum+=a[j];
        }
        System.out.println();
        System.out.println("평균은 "+sum/10);
    }
}
 

8.

9.

public class _09 {
    public static void main(String[] args) {
        int a[][] = new int[4][4];
        for(int i=0;i<a.length;i++)
        {
            for(int j=0;j<a[i].length;j++)
            {
                a[i][j]=(int)(Math.random()*10+1);
            }
        }
        for(int i=0;i<a.length;i++)
        {
            for(int j=0;j<a[i].length;j++)
            {
                System.out.print(a[i][j]+"\t");
            }
            System.out.println();
        }
    }
}
 

10.

public class _10 {
    public static void main(String[] args) {
        int a[][] = new int[4][4];
        int num1,num2;
        int n=0;
        
        while(n<10)
        {
            num1=(int)Math.round(Math.random()*3);
            num2=(int)Math.round(Math.random()*3);
            if(a[num1][num2]==0)
            {
                a[num1][num2]=(int)(Math.random()*10+1);
            }
            else
                n--;
            n++;
        }
        
        for(int i=0;i<4;i++)
        {
            for(int j=0;j<4;j++)
            {
                System.out.print(a[i][j]+"\t");
            }
            System.out.println();
        }
        }
}
 

11.

public class _13 {
    public static void main(String[] args) {
        for(int i=1;i<100;i++)
        {
            if(i%10==3 || i%10==6 || i%10==9)
            {
                if(i/10==3 || i/10==6 || i/10==9)
                {
                    System.out.println(i+" 박수 짝짝");
                }
                else
                    System.out.println(i+ " 박수 짝");
            }
            else if(i/10==3 || i/10==6 || i/10==9)
            {
                if(i%10==3 || i%10==6 || i%10==9)
                    System.out.println(i+ " 박수 짝짝");
                else
                    System.out.println(i+ " 박수 짝");
            }
            
        }
    }
}
 

14.

import java.util.Scanner;
public class _14 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String course [] = { "Java", "C++", "HTML5", "컴퓨터구조", "안드로이드"};
        int score[] = {95, 88, 76, 62, 55};
        
        while(true)
        {
            int n=0;
            System.out.print("과목 이름>>");
            String s = scanner.next();
            
            if(s.equals("그만"))
                break;
            else
            {
                int i=0;
                while(true)
                {
                    if(s.equals(course[i]))
                            {
                                System.out.println(s+"의 점수는 "+score[i]);
                                break;
                            }
                    else if(!s.equals(course[i]) && i==4)
                    {
                        System.out.println("없는 과목입니다.");
                        break;
                    }
                    i++;
                }
            }
            
            
        }
        scanner.close();
    }
}
 

15.

import java.util.Scanner;
import java.util.InputMismatchException;
public class _15 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        while(true)
        {
            System.out.print("곱하고자 하는 두 수 입력>>");
            try {
            int n = scanner.nextInt();
            int m = scanner.nextInt();
            System.out.println(n+"x"+m+"="+n*m);
            break;
            }
            catch(InputMismatchException e) {
                System.out.println("실수는 입력하면 안됩니다.");
                scanner.nextLine();
            }
        }
    }
}
 

16.

import java.util.Scanner;
public class _16 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("컴퓨터와 가위 바위 보 게임을 합니다.");
        String str[] = {"가위", "바위","보"};
        while(true)
        {
            int n = (int)(Math.random()*3);
            System.out.print("가위 바위 보!>>");
            String s = scanner.next();
            if(s.equals("그만")) {
                System.out.println("게임을 종료합니다...");
                break;
            }
            else if(str[n].equals("가위")&&s.equals("가위") || str[n].equals("바위")&&s.equals("바위") || str[n].equals("보")&&s.equals("보"))
            {
                System.out.println("사용자 = "+s+", 컴퓨터 = "+str[n]+", 비겼습니다.");
            }
            else if(str[n].equals("가위")&&s.equals("바위") || str[n].equals("바위")&&s.equals("보") || str[n].equals("보")&&s.equals("가위"))
            {
                System.out.println("사용자 = "+s+", 컴퓨터 = "+str[n]+", 사용자가 이겼습니다.");
            }
            else if(str[n].equals("가위")&&s.equals("보") || str[n].equals("바위")&&s.equals("가위") || str[n].equals("보")&&s.equals("바위"))
            {
                System.out.println("사용자 = "+s+", 컴퓨터 = "+str[n]+", 컴퓨터가 이겼습니다.");
            }
        }
        scanner.close();
    }
}