[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 start2
            if guess(mid) == -1:
                end = mid-1
            elif guess(mid) == 0:
                return mid
            else:
                start = mid+1
        return start