We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I‘ll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower
 1 : My number is higher
 0 : Congrats! You got it!

Example:

n = 10, I pick 6.

Return 6.

题意：猜一个数字，按照二分法的顺序来猜，猜大时提醒1，猜小时提醒-1，猜对时提醒0，问：在猜出来的数字是多少？
思路：按照二分法的顺序来猜，根据提示的大小选择左半部分还是右半部分。
java：

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int left=1;
	int right=n;
        while(left<=right)//按照二分法来猜
        {
        	int number=left+(right-left)/2;
        	count=guess(number);
        	if(count==0)
        		return number;//猜对直接返回
        	else if(count==1)//猜大时，选择左半部分
        		left=number+1;
        	else {
		　　right=number-1;//猜小时选择右半部分
			}       		
        }
        return -1;
    }
}

374. Guess Number Higher or Lower java