374.md

374. Guess Number Higher or Lower

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.

my thoughts:

1. use guess(n) to check the mid point

my solution:

**********26ms
# 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
        """
        l = 0
        r = n
        while guess((l+r)/2) != 0:
            if guess((l+r)/2) > 0:
                l = (l+r)/2 + 1
            else:
                r = (l+r)/2
        return (l+r)/2

my comments:

need to be careful with the board lines when divide the problem size into halves.
from other ppl's solution:

1. N/A