< Back 374. Guess Number Higher or Lower We're playing a guessing game, someone picks a number and we have to guess it. They tell us whether we've guessed the number using the guess() API, or receive a 1 or -1 response if the number is higher or lower, respectively. We use binary search to guess the number. The solution is as follows: class Solution: def guessNumber(self, n: int) -> int: l, r = 1, n while l <= r: m = (r + l) // 2 res = guess(m) if not res: return m elif res > 0: l = m + 1 else: r = m - 1 _ Time Complexity: O(log(n)) - We use binary search to find the number. _ Space Complexity: O(1) - We use constant space to retain our variables.