LeetCode Problem : Length of Last Word

Problem

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.

Code

int lengthOfLastWord(const char *s) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
    int len = strlen(s);
    int i = len - 1;
    while(i >= 0 && (s[i] == ' ' || s[i] == '\t'))
        --i;
    int j = i;
    while(j >= 0 && s[j] != ' ' && s[j] != '\t')
        --j;
    return (i - j);
}