LeetCode Guess Number Higher or Lower

// Data :2016.07.19
// Author :yqtao

/*********************************************************
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.
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//this prolem we use binary search//the very careful is meanNumber = (maxNumber - minNumber) / 2 + minNumber//and not mid=(start+end)/2,because it can overflowint guess(int num);int guessNumber(int n) {    int maxNumber = n, minNumber = 1;    while (true) {        int meanNumber = (maxNumber - minNumber) / 2 + minNumber;        int res = guess(meanNumber);        if (res == 0) {            return meanNumber;        }        else if (res == 1) {            minNumber = meanNumber + 1;        }        else {            maxNumber = meanNumber - 1;        }    }}