Type：easy
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.
Example:
Input:"Hello World"Output:5
给定一个字符串，要求输出最后一个空格后的字符串长度，若字符串最后是空格，输出之前最后一个没有空格的字符串长度。
先把字符串后面的空格删去即可。注意字符串erase函数的使用。
class Solution {
public:
int lengthOfLastWord(string s) {
int n = s.length();
int ret = 0;
for(int i=n-1; i>=0; i--){
if(s[i] == ' ') s.erase(i);
else break;
}
n = s.length();
for(int i=0; i<n; i++){
ret++;
if(s[i] == ' ') ret = 0;
}
return ret;
}
};
