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".

Solution:

  1. public class Solution {
  2.   public String simplifyPath(String path) {
  3.     Set<String> set = new HashSet<>(Arrays.asList("", ".", ".."));
  4.     Deque<String> deque = new ArrayDeque<>();
  6.     for (String token : path.split("/")) {
  7.       if (token.equals("..") && !deque.isEmpty()) 
  8.         deque.pollLast();
  10.       if (set.contains(token)) 
  11.         continue;
  13.       deque.addLast(token);
  14.     }
  16.     StringBuilder sb = new StringBuilder();
  18.     while (!deque.isEmpty()) {
  19.       sb.append("/" + deque.pollFirst());
  20.     }
  22.     return sb.length() == 0 ? "/" : sb.toString();
  23.   }
  24. }