71. Simplify Path

• categories: Code, Interview Question, leetcode, Medium
• source: https://leetcode.com/problems/simplify-path
• topics: String Manipulation, Stack

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.

Idea:

Use stack

class Solution:
    def simplifyPath(self, path: str) -> str:
        stack = deque()
        for s in path.split("/"):
            if not s:
                continue
            if s == "..":
                if stack:
                    stack.pop()
                continue
            if s == ".":
                continue
            stack.append(s)
        return "/" + "/".join(stack)