Simplify Path

Given an absolute path for a file (Unix-style), simplify it.

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

Corner Cases:
Did you consider the case where path = "/../"?
In this case, you should return "/".
Another corner case is the path might contain multiple slashes '/' together, such as "/home//foo/".
In this case, you should ignore redundant slashes and return "/home/foo".

Solution: Add an additional '/' at the end of 'path' for simply detecting the end.

class Solution {
public:
    string simplifyPath(string path) {
        string res;
        path += "/";
        size_t pos = path.find_first_of("/"), last = 0;
        while(pos != string::npos) {
            string s = path.substr(last, pos - last);
            if(s == "..") {
                if (!res.empty())
                    res.resize(res.find_last_of("/"));
            }
            else if (!s.empty() && s != ".")
            {
                res += "/";
                res += s;
            }
            last = pos + 1;
            pos = path.find_first_of("/", last);
        }
        return res.empty() ? "/" : res;
    }
};