LeetCode #151 Reverse Words in a String

Problem

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.

Solution

Method:

Time Complexity: O(n)

Space Complexity: O(n)

class Solution(object):
    def reverseWords(self, s):
        """
        :type s: str
        :rtype: str
        """
        t = s.split()
        res = ''
        idx = len(t) - 1
        
        while idx > 0:
            res += t[idx] + ' '
            idx -= 1
        if t:
            res += t[0]

        return res