Problem Description
Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a maximal substring consisting of non-space characters only.
Key Insights
- The last word can be found by identifying the last sequence of non-space characters in the string.
- Leading and trailing spaces should be ignored when determining the last word.
- A simple traversal from the end of the string can efficiently find the length of the last word without needing to split the entire string.
Space and Time Complexity
Time Complexity: O(n) - where n is the length of the string s, as we may need to traverse the entire string in the worst case. Space Complexity: O(1) - we are only using a few variables for counting and indexing, regardless of the input size.
Solution
To determine the length of the last word, we can iterate backward through the string, skipping spaces until we find the first non-space character. We then continue to count the characters until we reach another space or the beginning of the string. This approach avoids the need to split the string into words and works directly on the character array.