Reverse Words in a String

Problem Description

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. The returned string should not include any extra spaces.

Key Insights

• A word is a sequence of non-space characters, and there can be multiple spaces between words or leading/trailing spaces.
• The result should consist of words in reverse order, separated by a single space.
• We can use string manipulation techniques to trim spaces and reverse the word order efficiently.

Space and Time Complexity

Time Complexity: O(n), where n is the length of the input string s.
Space Complexity: O(1) if we consider the output space separately; otherwise, O(n) for storing the words.

Solution

The problem can be solved using string manipulation techniques. The basic steps are:

1. Split the string by spaces to extract words, which automatically handles multiple spaces.
2. Reverse the list of words.
3. Join the reversed list into a single string with a single space between words.

This approach uses a list to store the words temporarily, and the split and join operations are efficient for this problem size.

Code Solutions