Reverse Words in a String

reverse_words.py

"""
Description:
Given an input string , reverse the string word by word.
A word is defined as a sequence of non-space characters.
The input string does not contain leading or trailing spaces.
The words are always separated by a single space.

Example:
Input:  ["t","h","e"," ","s","k","y"," ","i","s"," ","b","l","u","e"]
Output: ["b","l","u","e"," ","i","s"," ","s","k","y"," ","t","h","e"]
"""

def reverseWords(s):
    """
    :type str: List[str]
    :rtype: void Do not return anything, modify str in-place instead.
    """
    n = len(s)
    s.reverse()
    spaces = [idx for (idx, c) in zip(range(n), s) if c == ' ']
    start = 0
    for i in spaces:
        s[start:i] = s[start:i][::-1]
        start = i + 1
    s[start:] = s[start:][::-1]