[LeetCode] Length of Last Word

Well, the basic idea is very simple. Start from the tail of s and move backwards to find the first non-space character. Then from this character, move backwards and count the number of non-space characters until we pass over the head of s or meet a space character. The count will then be the length of the last word.

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;
    }
};