(leetcode)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,i,cnt;
		len = s.length();
		cnt =0;

		while(s[len-1] == ' ') 
		{
			--len;
			if(len == 0) return 0;
		}
		if(len==1) return 1;
		for(i = len-1;i>=0;i--)
		{
			if(s[i] != ' ') ++cnt;
			else
				return cnt;
		}
		return cnt;
    }
};