Leetcode - Simplify Path

Question

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.

Ideas

• This is a stack question like Leetcode - Basic Calculator II where our .. relative directives immediately affect the last directory we processed (note here processed not the next directory in the list of directories we are processing)
• We want to first split our string of paths on a “/”
• Iterating through the directories
  • If curr is “.” or “” ignore it
  • If there is stuff in the stack and curr is “..”, pop from stack
  • Otherwise add to the stack

Don’t get tunnel vision

During this problem, I got tunnel vision trying to solve the problem where you can have multiple .. in a row d/b/../../ and I didn’t realize that my method wasn’t wrong, but rather I was mistaking the directories we are building up for our stack. When I solve problems, I need to try to prevent Tunnel Vision

Solution