LeetCode75-374-Guess-Number

🧠 Summary of Thoughts

• Binary Search
• Update low and high to mid + 1 or mid - 1
• mid = low + (high - low) / 2
• return -1

✅ Code（Java）

/** 
 * 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;
        int mid = 0;
        while (low <= high) {
            mid = low + (high - low) / 2;
            if (guess(mid) == -1) {
                high = mid - 1;
            } else if (guess(mid) == 1) {
                low = mid + 1;
            } else {
                return mid;
            }
        }
        return -1;
    }
}