[leetcode]71. Simplify Path简化路径

Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.

In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix

Note that the returned canonical path must always begin with a slash /, and there must be only a single slash / between two directory names. The last directory name (if it exists) must not end with a trailing /. Also, the canonical path must be the shorteststring representing the absolute path.

Example 1:

Input: "/home/"
Output: "/home"
Explanation: Note that there is no trailing slash after the last directory name.

Example 2:

Input: "/../"
Output: "/"
Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.

Example 3:

Input: "/home//foo/"
Output: "/home/foo"
Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.

Example 4:

Input: "/a/./b/../../c/"
Output: "/c"

题意

遇到"."的情况直接去掉，遇到".."删掉它上面挨着的一个路径， 求简化后的路径

思路

很接近real industry的题目

将input通过/分离出来， 利用Stack来模拟遇到"."和".."的情况

代码

 1 public class _71_SimplifyPath {
 2     public String simplifyPath(String path) {
 3         // corner case
 4         if (path.length() <= 1) return path;
 5         //split inout
 6         String[] input = path.split("/");
 7         Stack<String> stack = new Stack<>();
 8         for (String s : input) {
 9             if (s.equals("..")) {
10                 if (!stack.empty()) {
11                     stack.pop();
12                 }
13             } else if (s.equals(".") && !s.isEmpty()) {
14                 stack.push(s);
15             }
16         }
17         String result = " ";
18         if (stack.isEmpty()) return "/";
19         while (!stack.empty()) {
20             String cur = stack.pop();
21             result = "/" + cur + result;
22         }
23         return result;
24     }
25 }