LeetCode[Stack]: Simplify Path

Given an absolute path for a file (Unix-style), simplify it. 
For example, 
path = "/home/", => "/home" 
path = "/a/./b/../../c/", => "/c"

这个题目比较简单，用很常规的方法解决即可，测试的时候遇到什么问题再解决就行了。我的C++代码如下：

    string simplifyPath(string path) {
        string dir;
        stack<string> dirs;

        for (auto ch : path) {
            if (ch != ‘/‘) dir += ch;
            else if (!dir.empty()) {
                dirs.push(dir);
                dir.clear();
            }
        }

        if (!dir.empty()) {
            dirs.push(dir);
            dir.clear();
        }

        int popCount = 0;
        while (!dirs.empty()) {
            auto topDir = dirs.top();
            dirs.pop();

            if (!topDir.compare(".")) continue;
            else if (!topDir.compare("..")) ++popCount;
            else if (popCount) --popCount;
            else dir.insert(0, "/" + topDir);
        }

        return dir.empty() ? "/" : dir;
    }

时间性能如下图所示：