374. Guess Number Higher or Lower

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.

二分查找：简单的问题在编写过程中也遇到很多问题。

int guessNumber(int n) {        int maxNumber = n, minNumber = 1;        while (true) {            int meanNumber = (maxNumber - minNumber) / 2 + minNumber;            // Do NOT use (maxNumber+minNumber)/2 in case of over flow            int res = guess(meanNumber);            if (res == 0) {                 return meanNumber;            } else if (res == 1) {                minNumber = meanNumber + 1;            } else {                maxNumber = meanNumber - 1;            }        }    }

大佬在代码中已经提示了：

// Do NOT use (maxNumber+minNumber)/2 in case of over flow

还有用递归编写的话会超时（前面做了好多树的题目，习惯了）。