151. Reverse Words in a String

Given an input string, reverse the string word by word.

Example:  

Input: "the sky is blue",
Output: "blue is sky the".

Note:

• A word is defined as a sequence of non-space characters.
• Input string may contain leading or trailing spaces. However, your reversed string should not contain leading or trailing spaces.
• You need to reduce multiple spaces between two words to a single space in the reversed string.

Follow up: For C programmers, try to solve it in-place in O(1) space.

class Solution(object):
    def reverseWords(self, s):
        """
        :type s: str
        :rtype: str
        """
        return ' '.join(s.strip().split()[::-1])