LeetCode 58. 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.

这个题目只要注意如果字符串以‘ ’结尾的情况就行了例如"Hello World    "的返回值也是5

class Solution {
public:
    int lengthOfLastWord(string s) {
        size_t length=0;
        bool tag=false;
        for(int i=s.size()-1;i>=0;--i)
        {
            if(s[i]!=' ')
            {
                tag=true;
                ++length;
            }
            if(s[i]==' '&&tag)return length;
        }
        return length;
    }
};