53. 374. Guess Number Higher or Lower

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

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int low = 1;
        int high = n;
        while(low<=high){
            int mid = low+(high-low)/2;
            int pick = guess(mid);//call the given api
            if(pick==0){
                return mid;
            }else if(pick==-1){
                high=mid-1;
            }else{
                low=mid+1;
            }
        }
        return 0;
        
    }
}