leetcode 21: 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.

tips: 1. check corner situation.

2.  if initial situation is different from others, deal with it before go into loop.

3. if ending situation is different from other, insert a sentinel or a dummy value.

 

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if( *s == '\0') return 0;
        
        int len = *s == ' ' ? 0 : 1;
        
        while(  (*++s) != '\0' ) {
            if( *s != ' ') {
                if( *(s-1) != ' ') {
                    len++;
                } else {
                    len = 1;
                }
            } 
        }
        
        return len;
    }
};