374. Guess Number Higher or Lowe

换壳二分

/* 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 hi =n;
        int lo =1;
        int result = 0;
        while(lo<=hi)
        {
            int mid = lo+(hi-lo)/2;
            if(guess(mid)==0)
            {
                result=mid;
                break;
            }
            else if(guess(mid)==-1)
            {
                hi=mid-1;
            }
            else
                lo=mid+1;
        }
        return result;
    }
}