58. Length of Last Word

📝 Problem Details

• Title: 58. Length of Last Word
• Link: https://leetcode.com/problems/length-of-last-word/
• Difficulty: Easy
• Tags/Categories: Strings

💭What Were My Initial Thoughts?

- since we only care about the length of the last word of the string, we can start from the back of the string and interate inward
- constraints of the input being only alphabetical and spaces makes the problem somewhat trivial 
- the only edge case that really needs to be covered is if the end of the string has spaces before the word is encountered

🤔What Did I Struggle With?

~

💡 Explanation of Solution

~ same as intuition

⌛ Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(1)

💻 Implementation of Solution

class Solution {
public:
    int lengthOfLastWord(string s) { 
        int len = 0, tail = s.length() - 1;
        while (tail >= 0 && s[tail] == ' ') tail--;
        while (tail >= 0 && s[tail] != ' ') {
            len++;
            tail--;
        }
        return len;
    }
};