Solve the Easy-level Length of Last Word coding interview problem online in Python & JavaScript. Run your code against real test cases in the browser and study worked examples. It covers strings. Read the step-by-step solution and complexity analysis.

Length of Last Word – Solve Online in Python & JavaScript

Find the length of the last word in a given string.

Given a string s consisting of only printable ASCII characters, write a function `length_of_last_word(s: str) -> int` that returns the length of the last word in the string.

A word is defined as a maximal substring consisting of non-space characters only.

If there are no words in the string, return 0.

Note that the input string may contain leading or trailing spaces, and the words are separated by one or more spaces.

- A word is any maximal run of non-space characters.
- Leading, trailing, and repeated spaces should not count as part of a word.
- If the string contains only spaces, the answer is `0`.

Understand What Counts as a Word

- One straightforward approach is to split the string on whitespace.
- The last token is the last word, and its length is the answer.
- This is easy to read, but it creates a list of all words.

Simple Split-Based Idea

- The last word is closest to the end of the string.
- First skip trailing spaces.
- Then count characters until you reach another space or the beginning of the string.

Scan from the End

- After trailing spaces are skipped, `i` points at the last character of the last word.
- Move left while characters are not spaces, increasing a counter.
- If there was no word, the counter stays at `0`.

Count the Last Word Characters

- The final solution uses the end scan to avoid storing extra words.
- Time complexity is O(n) in the worst case.
- Space complexity is O(1).