EOJ-3342-交互题初体验

/**
 * 注意到10^9和-10^9是包含的
 * （这是一个闭区间）
 * 所以我这里的POSSIBLE_SCOPE_OF_DATA取了10^9+1
 * 
 * 用二分法猜数字
 * 
 * 注意交互题用的是System.out.flush();
 * 
 * 我本来以为要动用什么synchronized
 * 其实只要System.out去flush一下
 * 
 */

import java.util.Scanner;

public class Main {

    private final static int POSSIBLE_SCOPE_OF_DATA = 1000000001;
    private final static String BIGGER_THAN_THE_ANSWER = "big";
    private final static String SMALLER_THAN_THE_ANSWER = "small";
    private final static String GET_THE_ACCURATE_ANSWER = "equal";

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long leftEndPoint = -POSSIBLE_SCOPE_OF_DATA;
        long rightEndPoint = POSSIBLE_SCOPE_OF_DATA;
        long guessingNumber = (leftEndPoint + rightEndPoint) >>> 2;
        System.out.println(guessingNumber);
        System.out.flush();
        String replyOfInteractiveProgram;
        do {
            replyOfInteractiveProgram = in.nextLine();
            switch (replyOfInteractiveProgram) {
            case BIGGER_THAN_THE_ANSWER:
                rightEndPoint = guessingNumber;
                break;
            case SMALLER_THAN_THE_ANSWER:
                leftEndPoint = guessingNumber;
                break;
            case GET_THE_ACCURATE_ANSWER:
                break;
            }
            guessingNumber = (leftEndPoint + rightEndPoint) >>> 2;
            System.out.println(guessingNumber);
            System.out.flush();
        } while (!replyOfInteractiveProgram.equals(GET_THE_ACCURATE_ANSWER));
    }

}