[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

.

思路：从最后一个非空格字符往前遍历，当遍历到空格字符时，遍历的长度即为最后一个单词的长度

代码：

class Solution {
public:
int lengthOfLastWord(const char *s) {
int len=strlen(s);
if(len==0) return 0;
int res=0,last=len-1;
for(int i=len-1;i>=0;i--){
if(s[i]==' ') last--;
else break;
}
for(int i=last;i>=0;i--){
if(s[i]!=' ') res++;
else return res;
}
return res;
}
};