[LeetCode] Challenge log 374

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374. Guess Number Higher or Lower

No explainaton needed. It is a good code template for BS.

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’ll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

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-1 : My number is lower
 1 : My number is higher
 0 : Congrats! You got it!

Example:

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n = 10, I pick 6.

Return 6.
Soulution:
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# The guess API is already defined for you.
# @param num, your guess
# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
# def guess(num):

class Solution(object):
    def guessNumber(self, n):
        """
        :type n: int
        :rtype: int
        """
        low = 1
        high = n
        while low < high:
            mid = (low + high) // 2
            g = guess(mid)
            if g == 0:
                return mid
            elif g == 1:
                low = mid + 1
            else:
                high = mid
        return low
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