Simplify path

Time: O(N); Space: O(N); medium

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”

Example 5:

Input: path = “/a/../../b/../c//.//”

Output: “/c”

Example 6:

Input: path = “/a//b////c/d//././/..”

Output: “/a/b/c”

Corner Cases:

  1. Did you consider the case where path = “/../”?

In this case, you should return “/”.

  1. Another corner case is the path might contain multiple slashes ‘/’ together, such as “/home//foo/”.

In this case, you should ignore redundant slashes and return “/home/foo”.

[1]:

class Solution1(object):
    def simplifyPath(self, path):
        '''
        :type path: str
        :rtype: str
        '''
        stack, tokens = [], path.split("/")
        for token in tokens:
            if token == ".." and stack:
                stack.pop()
            elif token != ".." and token != "." and token:
                stack.append(token)
        return "/" + "/".join(stack)

[2]:

s = Solution1()
path = "/home/"
assert s.simplifyPath(path) == "/home"
path = "/../"
assert s.simplifyPath(path) == "/"
path = "/home//foo/"
assert s.simplifyPath(path) == "/home/foo"
path = "/a/./b/../../c/"
assert s.simplifyPath(path) == "/c"
path = "/a/../../b/../c//.//"
assert s.simplifyPath(path) == "/c"
path = "/a//b////c/d//././/.."
assert s.simplifyPath(path) == "/a/b/c"