# 71 Simplify Path

Given an absolute path for a file (Unix-style), simplify it.

For example,\
**path**=`"/home/"`, =>`"/home"`\
**path**=`"/a/./b/../../c/"`, =>`"/c"`

**Corner Cases:**

* Did you consider the case where path = "/../"?
* In this case, you should return "/".
* 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".

**The Idea:** This problem requires some Unix domain knowledge. `.` means current directory, so in terms of a path, it adds nothing and can be ignored. `..` means move up to parent directory, and `...` means move up recursively. Utilizing a stack is a natural solution because moving to a parent directory is equivalently to moving to the previous or most recent element in an array.

**Complexity:** O(n) time and space

```python
class Solution:
    def simplifyPath(self, path):
        """
        :type path: str
        :rtype: str
        """

        tokens = [token for token in path.split('/') if token != '' and token != '.']
        s = []

        for token in tokens:
            if token == '..':
                if s: # separated ifs for case where '...'
                    s.pop()
            else:
                s.append(token)

        return '/' + '/'.join(s)


obj = Solution()
print(obj.simplifyPath('/...')) # /...
print(obj.simplifyPath('/../')) # /
print(obj.simplifyPath('/')) # /
print(obj.simplifyPath('/a/./b/../../c/')) # /c
print(obj.simplifyPath('/home//foo/')) # /home/foo
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://maksimdan.gitbook.io/interview-practice-problems/leetcode_sessions/71-simplify-path.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.