[leetcode: Python]374. Guess Number Higher or Lower

题目：
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):

-1 : My number is lower
1 : My number is higher
0 : Congrats! You got it!
Example:
n = 10, I pick 6.

Return 6.
二分
方法一：性能39ms

# 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        """        left = 1        right = n        while left <= right:            # g =  left + ((right - left) >> 1)            g = int((right+left)/2)            if guess(g) == 1:                left = g+1            elif guess(g) == -1:                right = g-1            else:                return g        return left 

方法二：性能32ms

# 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        """        start = 1        end = n        if guess(n) == 0:            return n        while start<end:            mid = start + (end - start) // 2            if guess(mid) == -1:                end = mid-1            elif guess(mid) == 0:                return mid            else:                start = mid+1        return start