第71題，題目如下:
You are given an absolute path for a Unix-style file system, which always begins with a slash '/'. Your task is to transform this absolute path into its simplified canonical path.
The rules of a Unix-style file system are as follows:
- A single period
'.'represents the current directory. - A double period
'..'represents the previous/parent directory. - Multiple consecutive slashes such as
'//'and'///'are treated as a single slash'/'. - Any sequence of periods that does not match the rules above should be treated as a valid directory or file name. For example,
'...'and'....'are valid directory or file names.
The simplified canonical path should follow these rules:
- The path must start with a single slash
'/'. - Directories within the path must be separated by exactly one slash
'/'. - The path must not end with a slash
'/', unless it is the root directory. - The path must not have any single or double periods (
'.'and'..') used to denote current or parent directories.
Return the simplified canonical path.
Example 1:
Input: path = “/home/”
Output: “/home”
Explanation:
The trailing slash should be removed.
Example 2:
Input: path = “/home//foo/”
Output: “/home/foo”
Explanation:
Multiple consecutive slashes are replaced by a single one.
Example 3:
Input: path = “/home/user/Documents/../Pictures”
Output: “/home/user/Pictures”
Explanation:
A double period ".." refers to the directory up a level (the parent directory).
Example 4:
Input: path = “/../”
Output: “/”
Explanation:
Going one level up from the root directory is not possible.
Example 5:
Input: path = “/…/a/../b/c/../d/./”
Output: “/…/b/d”
Explanation:
"..." is a valid name for a directory in this problem.
Constraints:
1 <= path.length <= 3000pathconsists of English letters, digits, period'.', slash'/'or'_'.pathis a valid absolute Unix path.
先將路徑以”/”區隔出來，放到Stack當中。每次讀取時，有找到”.”時，則繼續讀取(push)；有找到”..”時，則將最末端的路徑去掉(pop)。最終再將Stack中剩下的路徑串聯起來(join)即得解答。
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