#71: Simplify Path

Author: papilo-cloud

Stacks/simplify_path.py

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+# 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 <= 3000
+# path consists of English letters, digits, period '.', slash '/' or '_'.
+# path is a valid absolute Unix path.
+
+
+class Solution:
+    def simplifyPath(self, path: str) -> str:
+        stack = []
+        token = path.split('/')
+        for str in token:
+            if str == '' or str == '.':
+                continue
+            if str == '..':
+                if stack:
+                    stack.pop()
+            else:
+                stack.append(str)
+        return '/'+'/'.join(stack)