[어서와 Java는 처음이지!_2019 Ver] 3장 Lab 도전문제 풀이

# 3장 Lab 도전문제 풀이

 

107p_도전문제)

package chap03;

import java.util.Scanner;

public class Advanced_107p {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		int x, y, min;
		
		Scanner input  = new Scanner(System.in);
		System.out.print("첫 번째 정수: ");
		x = input.nextInt();
		
		System.out.print("두 번째 정수: ");
		y = input.nextInt();
		
		if (x < y)
		{
			min = x;
		}
		else
		{
			min = y;
		}
		
		System.out.println("더 작은 수는 " + min);
	}
}

 

 

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110p_Lab 도전문제)

package chap03;
import java.util.Scanner;

public class Lab_Advanced_110p {

	public static void main(String[] args) {
		int score;
		
		Scanner input = new Scanner(System.in);
		System.out.print("성적을 입력하시오: ");
		score = input.nextInt();
		
		if(score >= 95)
		{
			System.out.println("학점 A+");
		}
		else if(score >= 90)
		{
			System.out.println("학점 A0");
		}
		else if(score >= 80)
		{
			System.out.println("학점 B");
		}
		else if(score >= 70)
		{
			System.out.println("학점 C");
		}
		else if(score >= 60)
		{
			System.out.println("학점 D");
		}
		else
		{
			System.out.println("학점 F");
		}
	}
}

 

 

---

 

112p_Lab 도전문제)

package chap03;
import java.util.Date;

public class Lab_Advanced_112p {

	public static void main(String[] args) {
		Date date = new Date();
		int currentMonth = date.getMonth();
		
		System.out.println("현재는 " + date + "월입니다.");
		if (currentMonth == 3 | currentMonth == 4 | currentMonth == 5)
		{
			System.out.println("봄입니다!");
		}
		else if(currentMonth == 6 | currentMonth == 7 | currentMonth == 8)
		{
			System.out.println("여름입니다!");
		}
		else if(currentMonth == 9 | currentMonth == 10 | currentMonth == 11)
		{
			System.out.println("가을입니다!");
		}
		else
		{
			System.out.println("겨울입니다!");
		}
	}
}

 

 

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118p_도전문제)

package chap03;
import java.util.Scanner;

public class Advanced_118p {
	
	public static void main(String[] args) {
		String month;
		
		Scanner scan = new Scanner(System.in);
		System.out.print("월의 이름을 입력하시오: ");
		month = scan.next();
		
		int monthNumber;
		switch (month)
		{
		case "January":
			monthNumber = 1;
			break;
		case "February":
			monthNumber = 2;
			break;
		case "March":
			monthNumber = 3;
			break;
		case "April":
			monthNumber = 4;
			break;
		case "May":
			monthNumber = 5;
			break;
		case "June":
			monthNumber = 6;
			break;
		case "July":
			monthNumber = 7;
			break;
		case "August":
			monthNumber = 8;
			break;
		case "September":
			monthNumber = 9;
			break;
		case "October":
			monthNumber = 10;
			break;
		case "November":
			monthNumber = 11;
			break;
		case "December":
			monthNumber = 12;
			break;
		default:
			monthNumber = 0;
			break;
		}
		
		System.out.println(monthNumber);
	}
}

 

 

---

 

120p_Lab 도전문제)

package chap03;
import java.util.*;

public class Lab_Advanced_120p {

	public static void main(String[] args) {
		int month;
		int days = 0;
		
		System.out.println("일수를 알고 싶은 월을 입력하시오:");
		Scanner scan = new Scanner(System.in);
		
		month = scan.nextInt();
		switch (month)
		{
		case 4:
		case 6:
		case 9:
		case 11:
			days = 30;
			break;
		case 2:
			if(month % 400 == 0)
			{
				days = 29;
			}
			else if((month % 4 == 0) && (month % 100 != 0))
			{
				days = 29;
			}
			else
			{
				days = 28;
			}
			break;
		default:
			days = 31;
			break;
		}
		System.out.println(month + "월의 날수는 " + days);
	}
}

 

+ 윤년

: 2월의 일 수가 평년인 경우 28일에서 1일 추가된 29일까지 있는 해

 

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125p_도전문제)

package chap03;
import java.util.*;

public class Advanced_125p {

	public static void main(String[] args) {
		int num;
		int i = 0;
		
		System.out.print("숫자를 입력하시오: ");
		Scanner scan = new Scanner(System.in);
		num = scan.nextInt();
		
		while (i <= num - 1)
		{
			if (i == num - 1)
			{
				System.out.print(i);
				i++;
			}
			else
			{
				System.out.print(i + ", ");
				i++;
			}
		}
	}
}

 

 

---

 

126p_도전문제)

package chap03;
import java.util.Scanner;

public class Advanced_126p {

	public static void main(String[] args)
	{
		int num;
		int sum = 0;
		int i = 1;
		
		System.out.print("숫자를 입력하시오: ");
		Scanner scan2 = new Scanner(System.in);
		num = scan2.nextInt();
		
		while(i <= num)
		{
			sum += i;
			i++;
		}
		
		System.out.println("1에서 " + num + "까지의 합은 " + sum + "입니다.");
	}
}

 

 

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130p_Lab 도전문제)

package chap03;

import java.util.*;

public class Lab_Advanced_130p {

	public static void main(String[] args) {
		int x, y, r, w, z;
		
		System.out.print("두 개의 정수를 입하시오: ");
		Scanner scan = new Scanner(System.in);
		
		x = scan.nextInt();
		y = scan.nextInt();
		
		w = x;
		z = y;
		
		while(y != 0)
		{
			r = x % y;
			x = y;
			y = r;
		}
		
		System.out.println("최소 공배수: " + (w*z/x));
	}
}

 

 

---

 

134p_도전문제)

package chap03;

import java.util.*;

public class Advanced_134p {

	public static void main(String[] args) {
		long fact = 1;
		int n;
		
		System.out.println("정수를 입력하시오: ");
		Scanner scan = new Scanner(System.in);
		n = scan.nextInt();
		
		for (int i = 1; i <= n; i++)
		{
			fact = fact * i;
		}
		
		System.out.printf("%d!의 결과: %d", n, fact);
	}

}

 

실행 결과 26! 의 값부터 오버플로우가 발생함을 확인할 수 있었다.

 

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138p_Lab 도전문제)

package chap03;

import java.util.*;
import java.util.Scanner;
import java.util.random.*;

public class Lab_Advanced_138p {

	public static void main(String[] args) {
		Random generator = new Random();
		
		int number = generator.nextInt(6) + 1;
		
		if (number % 2 == 0)
		{
			System.out.printf("뽑은 수 %d는 짝수입니다. 승리하였습니다.", number);
		}
		else
		{
			System.out.printf("뽑은 수 %d는 홀수입니다. 패배하였습니다.", number);
		}
	}
}

 

 

---

 

140p_도전문제)

package chap03;

public class Advanced_140p {

	public static void main(String[] args) {
		
		for (int i = 2; i <= 9; i++)
		{
			for (int k = 1; k <= 9; k++)
			{
				System.out.println(i + " x " + k + " = " + (k * i) );
				System.out.println();
			}
			
			System.out.println();
			System.out.println();
		}
	}
}

 

 

---

 

146p_Lab 도전문제)

package chap03;

import java.util.*;
import java.util.Scanner;
import java.util.random.*;

public class Lab_Advanced_146p {

	public static void main(String[] args) {
		Random generator = new Random();
		int answer = generator.nextInt(100);
		int guess;
		
		Scanner scan = new Scanner(System.in);
		int tries = 0;
		
		do {
			System.out.print("정답을 추측해보세요: ");
			guess = scan.nextInt();
			tries++;
			
			if(guess > answer)
			{
				System.out.println("제시한 정수가 높습니다.");
			}
			
			if (guess < answer)
			{
				System.out.println("제시한 정수가 낮습니다.");
			}
		} while (guess != answer);
		
		System.out.printf("%d번의 시도 끝에 정답을 맞히셨습니다!", tries);
	}
}

 

 

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148p_Lab 도전문제)

package chap03;

import java.util.*;

public class Lab_Advanced_148p {

	public static void main(String[] args) {
		int odds = 1;
        final int n = 45;
        final int k = 6;
        final int matchingNumbers = 3;

        for (int i = 1; i <= matchingNumbers; i++) {
            odds = odds * (k - i + 1) / i;
        }

        int remainingNumbers = k - matchingNumbers;
        int remainingBalls = n - k;

        for (int i = 1; i <= remainingNumbers; i++) {
            odds = odds * (remainingBalls - i + 1) / i;
        }

        System.out.println("로또 5등 당첨 확률: 1/" + odds);	
	}
}