[LeetCode/LintCode] Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

class Solution {
public:
    int lengthOfLastWord(string s) {
        int len = s.length();
        int i=len-1;
        while(s[i] == ' ')i--;
        int p = i;
        for(;i>=0;i--) if(s[i] == ' ') break;
        return p-i;
    }
};