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.
两个下标，head搜索非空格元素，last搜索head后的第一个空格或者字符串结尾。检测到单词后保存至lastlen里。
class Solution {
public:
int lengthOfLastWord(string s) {
const unsigned int len = s.size();
unsigned int head,last,lastlen;
head = ;
last = ;
lastlen = ;
if (!len)
;
) {
// search for the first non-space character
while ((s[head] == ' ') && (head != len))
head ++;
if (head == len)
return lastlen;
last = head；
while ((last != len) && (s[last] != ' '))
last ++;
if (last == len)
return last - head;
else {
lastlen = last - head;
head = last;
}
}
}
};