374. Guess Number Higher or Lower 简单的二分法运用

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.

简单的猜高猜低，运用二分法折半寻找。
在做题过程中，遇到了Time limit exceeded 百思不得其解 
另外发现 自己对于一般的算法没有什么概念，每次做题都是从简单的数学原创方法开始，
找时间要去看一下算法的归纳，这样就可以在看见题目的同时知道对应的什么算法。
下面是程序：

// Forward declaration of guess API.
// @param num, your guess
// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num);

class Solution {
public:
    int guessNumber(int n) {
        if (guess(n) == 0) return n;
        int left = 1, right = n;
        while (left < right) {
            int mid = left + (right - left) / 2, t = guess(mid);
            if (t == 0) return mid;
            else if (t == 1) left = mid;
            else right = mid;
        }
        return left;
    }
};