Given an absolute path for a file (Unix-style), simplify it. For example, path = "/home/", => "/home" path = "/a/./b/../../c/", => "/c" http://leetcode.com/onlinejudge#question_71

leetcode_simplify_path.cpp

void update(vector<string>& s, const string& t) {
    if (t == ".")
        ;
    else if (t == "..") {
        if (!s.empty())
            s.pop_back();
    }
    else
        s.push_back(t);
}

class Solution {
public:
    string simplifyPath(string path) {
        vector<string> s;
        int prev = -1;
        for (int i = 0; i < path.length(); ++i)
            if (path[i] == '/') {
                if (prev != -1 && prev != i)
                    update(s, path.substr(prev, i - prev));
                prev = i + 1;
            }
        if (prev != path.length())
            update(s, path.substr(prev, path.length() - prev));
        if (s.empty())
            return "/";
        string ret;
        for (int i = 0; i < s.size(); ++i)
            ret.append("/").append(s[i]);
        return ret;
    }
};