guess-number-higher-or-lower

// 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 {
    long long lb;
    long long hb;
public:
    int guessNumber(int n) {
        lb = 1;
        hb = n;
        if (lb >= hb) {
            return lb;
        }
        int g = (lb + hb) / 2;
        int r = guess(g);
        while (r != 0) {
            if (r < 0) {
                hb = g - 1;
            }
            else {
                lb = g + 1;
            }
            if (lb >= hb) {
                return lb;
            }
            g = (lb + hb) / 2;
            r = guess(g);
        }
        return g;
    }
};

https://leetcode.com/problems/guess-number-higher-or-lower/