Simplify Path in Python

Suppose we have an absolute path for a file (Like Unix File system), we have to simplify it. Or in other words, we have to convert it to the canonical path. In the UNIX-style file system, a period ‘.’ refers to the current directory. And a double period ‘..’ moves the directory up a level (Parent directory). The properties of canonical paths are as follows.

• Path must always begin with a slash /
• There must be only a single slash / between two directory names.
• Last directory name (if it exists) must not end with a trailing /.
• Canonical path must be the shortest string representing the absolute path.

So for example, if the given paths are “/home/”, “/../” and “/home//user/”, then the converted paths are “/home”, “/”, and “/home/user”

Let us see the steps −

• take a list st, and put ‘/’ into it
• a := a list of strings after splitting the given path with the delimiter ‘/’
• for each element i in a
  • if i is double period, then
    • if length of st > 1, then delete last element from st, otherwise continue
  • else if i is single period, then continue
  • else if is not empty string, then insert (‘/’ concatenate i) into st
• if st has only one element, then return ‘/’
• return after concatenating all elements present in st

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def simplifyPath(self, a):
      st = ['/']
      a = a.split("/")
      for i in a:
         if i == '..':
            if len(st) > 1:
               st.pop()
            else:
               continue
         elif i == '.':
            continue
         elif i != '':
            st.append("/" + str(i))
      if len(st) == 1:
         return "/"
      return "".join(st[1:])
ob1 = Solution()
print(ob1.simplifyPath("/home/"))
print(ob1.simplifyPath("/../"))
print(ob1.simplifyPath("/home//user/"))

Input

"/home/"
"/../"
"/home//user/"

Output

/home
/
/home/user