LeetCode 374 - 猜数字大小

class Solution:
    def guessNumber(self, n: int) -> int:
        head, tail = 1, n
        while head <= tail:
            mid = (head + tail) // 2
            result = guess(mid)
            if result < 0:
                tail = mid - 1
            elif result > 0:
                head = mid + 1
            else:
                return mid
        return head