Simplify Directory Path

• Time : $O(|A|)$
• Space : $O(|A|)$

vector<string> parse(string A) {
    vector<string> res;
    string now = "";
    for(int i = 0; i < A.size(); i++) {
        if(A[i] == '/') {
            if(now.length()) res.push_back(now);
            now = "";
        } else now.push_back(A[i]);
    }
    if(now.length()) res.push_back(now);
    return res;
}
string Solution::simplifyPath(string A) {
    vector<string> token = parse(A);
    vector<string> simple;
    for(auto t : token) {
        if(t == ".") continue;
        else if(t == "..") {
            if(!simple.empty()) simple.pop_back();
        } else simple.push_back(t);
    }
    string res = "";
    for(auto& s : simple) res += "/" + s;
    return res == "" ? "/" : res;
}