LeetCode Length of Last word

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        const char *p,*q;
        p=s;
        q=p+strlen(p)-1;
        
        while(p<q)
        {
            if(*q==' ')
                q--;
            else
                break;
        }

        int i=0;
        while(*q!=' '&&p<=q)
        {
            q--;
            i++;
        }
        return i;
    }
};