another_cpp

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;
    }
};

cpp

class Solution {
public:
    int lengthOfLastWord(string s) {
        int result = 0; int prev = 0;
        for (size_t i = 0; i < s.size(); i++) {
            if (s[i] != ' ') {
                result += 1;
            } else {
                if (result != 0) {
                    prev = result;
                }   
                result = 0;
            }                
        }
        
        if (result != 0) {
            return result;
        } else {
            return prev;
        }
    }
};

py

class Solution:
    def lengthOfLastWord(self, s: str) -> int:
        result = 0; prev = 0
        for ch in s:
            if ch != ' ':
                result += 1
            else:
                if result != 0:
                    prev = result
                result = 0
                
        return result if result != 0 else prev