374. Guess Number Higher or Lower

不定期更新leetcode解题java答案。

采用pick one的方式选择题目。

题意为给定一个范围，1~N，给定一个固定数，随机进行猜数，尽快用程序获取猜得结果。每次猜错会给出猜想大了(返回-1)或小了(返回1)的提示。

很容易想到用二分进行猜数（需要注意的是为了防止两数相加和超出int的上限，分开进行处理），代码如下：

/* The guess API is defined in the parent class GuessGame.
   @param num, your guess
   @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
      int guess(int num); */

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int start = 0, end = n, guessNum = 0;
        int result = 1;
        while(result != 0){
            if(result == 1)
                start = guessNum;
            else
                end = guessNum;
            guessNum = start / 2 + end / 2 + (start % 2 + end % 2 == 0 ? 0 : 1);
                
            result = guess(guessNum);
        }
        return guessNum;
    }
}