374. Guess Number Higher or Lower

problem

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.

solution

不用生成列表的二分

因为最终肯定能猜到判断条件用
while 1：

# 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
        """
        head = 1
        end = n+1
        while 1:
            mid = (head+end)/2
            result = guess(mid)
            if not result:
                return mid
            if result > 0:
                head =  mid
            if result < 0:
                end = mid