卖萌的弱渣

I am stupid, I am hungry.

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):

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

Example:

n = 10, I pick 6.

Return 6.

Solution

  • Binary search
(Guess-Number-Higher-or-Lower.py) download
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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
        """
        l = 1
        r = n

        while l <=r :
            m = (l+r)/2
            ret = guess(m)
            if ret == 0:
                return m
            elif ret < 0:
                r = m-1
            else:
                l = m+1

  return l