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.

从头开始记录字符串的长度，如果是最后一个字符串输出。

class Solution {public:    int lengthOfLastWord(string s) {        int n=s.length();        int l=0;        int l_pre=0;        for(int i=0;i

　　

只有后面是字符串的话，才改变length 为0

class Solution {public:    int lengthOfLastWord(string s) {        int n=s.length();        int l=0;        bool start=true;        for(int i=0;i