71. Simplify Path.md

71. Simplify Path

https://leetcode.com/problems/simplify-path/

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.

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 shortest string representing the absolute path.

Example 1:

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

Example 2:

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

Example 4:

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

Constraints:

• 1 <= path.length <= 3000
• path consists of English letters, digits, period '.', slash '/' or '_'.
• path is a valid Unix path.

代码

• Using stack

class Solution(object):
    def simplifyPath(self, path):
        stack = []
        for p in path.split("/"):
            if p == "..":
                if stack:
                    stack.pop()
			elif p == "." or not p:
                continue
            else:
                stack.append(p)
       
    	res = "/" + "/".join(stack)
        return res