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.

   int lengthOfLastWord(const char *s) {  
     int i = 0;  
     int cnt = 0;  
     int j = strlen(s) - 1;  
     while(s[j] == ' ')j--;  
     while(i<=j)  
     {  
       if(s[i] == ' ')  
       {  
         cnt = 0;  
       }  
       else  
       {  
         cnt++;  
       }  
       i++;  
     }  
     return cnt;  
   }