71. Simplify Path

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

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

click to show corner cases.
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".

此题刚开始看着比较懵逼，不知道怎么求解，但是慢慢想想其实还是很简单的，可以忽略 ./ (代表当前目录)，遇到 ../ 代表上一层目录，可以在对目录遍历的过程中不断的保存当前合法的路径，然后遇到 ../ 将当前路径弹出一个文件夹即可。

string simplifyPath(string path) {        vector<string> res;        for (auto it = path.begin(); it != path.end();){            it++;            auto j = find(it, path.end(), '/');            string str = string(it, j);            if (!str.empty() && str != "."){                if (str == ".."){                    if (!res.empty())res.pop_back();                }                else res.push_back(str);            }            it = j;        }        ostringstream out;        if (res.empty())out << '/';        else             for (auto x : res)out << '/' << x;        return out.str();    }