LeetCode 151: Reverse Words in a String Solution

Master LeetCode problem 151 (Reverse Words in a String), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

151. Reverse Words in a String

Medium

Two Pointers String

Problem Explanation

Explanation:

To solve this problem, we can follow these steps:

Trim the input string to remove leading and trailing spaces.
Split the input string by spaces to extract individual words.
Reverse the list of words.
Join the reversed words with a single space to form the final result string.

Time complexity analysis:

Splitting the string into words takes O(n) time, where n is the length of the input string.
Reversing the list of words takes O(n) time.
Joining the words back into a string takes O(n) time. Hence, the overall time complexity of this approach is O(n).

Space complexity analysis:

The space complexity is O(n) where n is the length of the input string, as we are storing the split words in a list.

Solution Code

class Solution {
    public String reverseWords(String s) {
        String[] words = s.trim().split("\\s+");
        StringBuilder result = new StringBuilder();

        for (int i = words.length - 1; i >= 0; i--) {
            result.append(words[i]);
            if (i > 0) {
                result.append(" ");
            }
        }

        return result.toString();
    }
}

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What is the time complexity of LeetCode 151 (Reverse Words in a String)?

The time complexity for LeetCode 151 (Reverse Words in a String) varies by solution. Check the detailed explanation section for specific complexities in Java, C++, and Python implementations.

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