面试题33：简化目录路径

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".

 1 class Solution {
 2 public:
 3     string simplifyPath(string path) {
 4         int n = path.size();
 5         stack<string> s;
 6         string dir;
 7         for (int i = 0; i < n; i++) {
 8             if (path[i] == '/') {
 9                 if (!dir.empty()) {
10                     s.push(dir);
11                     dir.clear();
12                 }
13             } else {
14                 dir.push_back(path[i]);
15             }
16         }
17         if(!dir.empty()) s.push(dir);
18 
19         string res;
20         int count = 0;
21         while (!s.empty()) {
22             string str = s.top();
23             s.pop();
24             if (str == ".") {
25                 continue;
26             } else if (str == "..") {
27                 count++;
28             } else {
29                 if (count > 0) {
30                     count--;
31                 } else {
32                     res = "/" + str + res;
33                 }
34             }
35         }
36         if(res.length() == 0) return "/";
37         return res;
38     }
39 };