Reverse Word In A String

Reverse word in a String

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.

Intuition

If we translate the sentence to a list of words (ignoring extra space), this problem will be reduced to reverse a simple list.

Solution

class  Solution:

def  reverseWords(self, s: str) -> str:

	words = list(filter(lambda  w: w!= '', s.split(' ')))

	for i in  range(len(words) // 2):

		words[i], words[len(words) - (i + 1)] = words[len(words) - (i + 1)], words[i]

	return  ' '.join(words)