Introduction

In this blog post, we will explore how to solve the LeetCode problem "151" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

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 <= 104 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?

Explanation

Here's an efficient solution to reverse the order of words in a string, addressing the constraints of extra spaces and in-place (if possible) requirements.

• Split and Filter: Split the input string into a list of words, removing leading/trailing spaces and handling multiple spaces between words by filtering out empty strings.
• Reverse: Reverse the order of the words in the list.

• Join: Join the reversed list of words back into a string, using a single space as a separator.

• Time Complexity: O(n), where n is the length of the input string.

• Space Complexity: O(n) due to the creation of a list of words and the final reversed string. If in-place modification were possible in Python strings (which it isn't), the space complexity could be reduced to O(1).

Code

    def reverse_words(s):
    """
    Reverses the order of words in a string, handling extra spaces.

    Args:
        s: The input string.

    Returns:
        The string with words reversed and extra spaces removed.
    """
    words = s.split()
    words = [word for word in words if word]  # Remove empty strings (multiple spaces)
    words.reverse()
    return " ".join(words)