guess_number.py

# We are playing the Guess Game. The game is as follows:

# I pick a number from 1 to n. You have to guess which number I picked.

# Every time you guess wrong, I will tell you whether the number I picked is higher or lower
# than your guess.

# You call a pre-defined API int guess(int num), which returns three possible results:

# -1: Your guess is higher than the number I picked (i.e. num > pick).
# 1: Your guess is lower than the number I picked (i.e. num < pick).
# 0: your guess is equal to the number I picked (i.e. num == pick).
# Return the number that I picked.


# Example 1:
# Input: n = 10, pick = 6
# Output: 6

# Example 2:
# Input: n = 1, pick = 1
# Output: 1

# Example 3:
# Input: n = 2, pick = 1
# Output: 1
 

# Constraints:

# 1 <= n <= 231 - 1
# 1 <= pick <= n


# The guess API is already defined for you.
# @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
# def guess(num: int) -> int:

class Solution:
    def guessNumber(self, n: int) -> int:
        left = 0
        right = n
        while left <= right:
            mid = (left+right)//2
            if guess(mid) == 0: # type: ignore
                return mid
            elif guess(mid) == -1: # type: ignore
                right = mid - 1
            else:
                left = mid + 1