LeetCode 151 Reverse Words in a String

LeetCode

Given an input string s, reverse the order of the words.

A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.

Return a string of the words in reverse order concatenated by a single space.

Note that s may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.

Example 1:

Input: s = “the sky is blue”
Output: “blue is sky the”

Example 2:

Input: s = “  hello world  “
Output: “world hello”
Explanation: Your reversed string should not contain leading or trailing spaces.

Example 3:

Input: s = “a good   example”
Output: “example good a”
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.

Constraints:

1 <= s.length <= 10<sup>4</sup> s contains English letters (upper-case and lower-case), digits, and spaces ' '.
There is at least one word in s.

Follow-up: If the string data type is mutable in your language, can you solve it *in-place with O(1) extra space?

题目大意：

反转字符串中的单词顺序

解题思路：

N/A

解题步骤：

N/A

注意事项：

1. word不能为空，单词之间可能含多个空格

Python代码：

def reverseWords(self, s: str) -> str:
	words = s.split(' ')
	words_without_space = [word for word in words if word]
	return ' '.join(words_without_space[::-1])

算法分析：

时间复杂度为O(n)，空间复杂度O(n)