Guess Number Higher or Lower

题目描述：

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.

其实我觉得这个题难在读懂提，读懂题就好说了，用二分法搞定

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