Guess_Number_Higher_or_Lower.cpp

// 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) {
        int left = 1, right = n;
        while(left <= right) {
            int mid = left + (right - left) / 2;
            if(!guess(mid)) {
                return mid;
            }
            if(guess(mid) == 1) {
                left = mid + 1;
            } else if(guess(mid) == -1) {
                right = mid - 1;
            }
        }
        return n;
    }
};