UpAndDown.java

package blog;
import java.util.Scanner;

public class UpAndDown {

	private static int firstRun = 1;
	private static int meWin = 0;
	private static int comWin = 0;
	private static final String ABOVE = "* Input is A B O V E from target *";
	private static final String BELOW = "* Input is B E L O W from target *";
	
	private static Scanner s = new Scanner(System.in);
	
	public static int generateRandomByRange(int min, int max) {
		return (int) ( Math.random() * ( max - min + 1 ) + min );
	}

	public static void main(String[] args) {

		while(true){
			System.out.println("==== Up & Down Game II+ ====");
			System.out.println("    (Human vs Kizuna Ai)    ");
			System.out.println();
			System.out.println("1. Game Start");
			System.out.println("2. Game Score");
			System.out.println("3. End Game");
			System.out.print("\n> ");

			int menuSelect = Integer.parseInt(s.nextLine());

			if(menuSelect==1)  game();
			else if(menuSelect==2) {
				switch(firstRun) {
				case 1: 
					System.out.println("There is no recorded score. "
							+ "First, play a game! \n");
					break;
				default:
					System.out.println("Me Win: " + meWin);
					System.out.println("Com(Ai) Win: " + comWin);
					System.out.println();
				}
			} else if(menuSelect==3) {
				System.out.println("\nThank you for playing!");
				System.exit(0);
			} else {
				System.out.println("Enter correct number please! (1~3)\n");
			}

		}        
	} 

	public static void game() {

		boolean isFirstTurn = true;
		int upNum = 99;
		int downNum = 1;

		int pick = generateRandomByRange(1, 99);

		System.out.println("<< Game Start >>");           


		while(true) {            

			// 0: 컴퓨터, 1: 나
			int whoTheFirst = generateRandomByRange(0, 1); 

			if(isFirstTurn && whoTheFirst==0)
				System.out.println("First player is Ai!\n");
			else if(isFirstTurn && whoTheFirst==1)
				System.out.println("First Player is YOU!\n");

			int sw1 = 0;	// ABOVE, BELOW 스위치 (1: above, -1: below)
			int meInputNum = 0;

			if (!isFirstTurn || whoTheFirst == 1)
			{
				System.out.print("Input Number(Me): ");
				meInputNum = Integer.parseInt(s.nextLine());

				// UP = 1; DOWN = -1;            

				if ( 0 >= meInputNum  || meInputNum >= 100 )
					System.out.println("Enter number between 1~99 please!\n");

				else if ( pick < meInputNum ) {
					// 입력한 값이 픽값보다 클 경우
					System.out.println(ABOVE + "\n");
					sw1 = 1;
					if ( upNum > meInputNum)
						upNum = meInputNum;

				} else if ( pick > meInputNum ) {
					// 입력한 값이 픽값보다 작을 경우
					System.out.println(BELOW + "\n");
					sw1 = -1;
					if ( downNum < meInputNum)
						downNum = meInputNum;

				} else if ( pick == meInputNum ) {
					System.out.println("* C O R R E C T *");
					System.out.println("* Y O U W I N ! *");
					System.out.println();
					meWin++;
					firstRun = 0;
					System.out.println("Your victory count is: " + meWin + "\n");
					break;
				}
			}

			// computer
			try {
				Thread.sleep(generateRandomByRange(500, 1000));	// 생각하는 척
			} catch (InterruptedException e) {
				e.printStackTrace();
			}            

			int comNum = 0;
			if (isFirstTurn && whoTheFirst == 1) {
				// 첫판인데 먼저 시작한 사람이 '나'인 경우
				if ( sw1 == -1 )
					comNum = generateRandomByRange(meInputNum + 1, 99);

				else if( sw1 == 1 )
					comNum = generateRandomByRange(1, meInputNum - 1);
				/*
				 * 앞에 '나'의 결과가 below인 경우: meInputNum + 1부터 99까지 던짐
				 * 앞에 '나'의 결과가 above인 경우: 1부터 meInputNum - 1까지 던짐
				 */

			} else if (isFirstTurn && whoTheFirst == 0) {
				// 만약 컴퓨터가 첫 턴인 경우 아무 숫자나 던진다.
				comNum = generateRandomByRange(1, 99);

			}	else {       
				comNum = generateRandomByRange((downNum + 1), (upNum - 1));
				// else의 경우 downNum(나온 숫자 중 최소값) + 1부터 upNum(나온 숫자 중 최대값) - 1까지의 수를 던짐

			}

			System.out.println("Ai's Input: " + comNum );

			if ( pick < comNum ) {
				System.out.println(ABOVE + "\n");
				sw1 = 1;
				if ( upNum > comNum )
					upNum = comNum;
			} else if ( pick > comNum )	{
				System.out.println(BELOW + "\n");
				sw1 = -1;
				if ( downNum < comNum )
					downNum = comNum;
			} else if ( pick == comNum ) {
				System.out.println("* C O R R E C T *");
				System.out.println("* Winner is AI!! *");
				System.out.println("* You lose. *");
				System.out.println();
				comWin++;
				firstRun = 0;
				break;
			}

			isFirstTurn = false;

		} 

	}

}