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String manipulation is a common coding interview topic, and this problem is a great example of working with substrings efficiently. Let’s solveLeetCode 58: Length of Last Word using a straightforward approach.

🚀 Problem Description

Given a strings consisting of words and spaces, return the length of the last word in the string.

• A word is defined as a maximal substring consisting of non-space characters only.

💡 Examples

Example 1

Input:s="Hello World"Output:5Explanation:Thelastwordis"World"withlength5.

Example 2

Input:s="fly me to the moon"Output:4Explanation:Thelastwordis"moon"withlength4.

Example 3

Input:s="luffy is still joyboy"Output:6Explanation:Thelastwordis"joyboy"withlength6.

🏆 JavaScript Solution

The problem can be solved by trimming unnecessary spaces and locating the last word efficiently.

Implementation

varlengthOfLastWord=function(s){constwords=s.trim().split('');returnwords[words.length-1].length;};

🔍 How It Works

1. Trim the String:
   • Remove leading and trailing spaces usingtrim() to simplify the logic.
2. Split the String:
   • Usesplit(' ') to divide the string into words based on spaces.
3. Get the Last Word:
   • Access the last element of the array (words[words.length - 1]) and return its length.

🔑 Complexity Analysis

• > Time Complexity:O(n) is the length of the string. Trimming and splitting the string both run in linear time.
• > Space Complexity:O(n), as splitting creates an array of words.

Alternative Solution (No Split)

For improved space efficiency, traverse the string backward to find the last word:

varlengthOfLastWord=function(s){letlength=0;leti=s.length-1;// Skip trailing spaceswhile(i>=0&&s[i]===''){i--;}// Count characters of the last wordwhile(i>=0&&s[i]!==''){length++;i--;}returnlength;};

🔑 Complexity Analysis (Alternative Solution)

• > Time Complexity:O(n), as we traverse the string once.
• > Space Complexity:O(1), as no extra data structures are used.

📋 Dry Run

Input:s = "fly me to the moon"

Output:4

✨ Pro Tips for Interviews

1. Clarify constraints:

   • Can the string be empty?
   • Are there multiple spaces between words?

2. Optimize for edge cases:

   • Input with only spaces (" " →0).
   • Single-word input ("hello" →5).

📚 Learn More

Check out the full explanation and code walkthrough on my Dev.to post:
👉Length of Last Word - JavaScript Solution

How would you solve this problem? Let’s discuss! 🚀

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