LeetCode 344. Reverse String

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "hello", return "olleh".

Maybe, the point to watch out here is the last '\0'??

    string reverseString(string s) {
        if(s.size() <= 1) return s;
        int i = 0;
        int j = s.size() - 1;
        while(i < j) {
            swap(s[i], s[j]);
            i++;
            j--;
        }
        return s;
    }