Simplify Directory Path

Given a string A representing an absolute path for a file (Unix-style).

Return the string A after simplifying the absolute path.

Note:
  1. Absolute path always begin with ’/’ ( root directory ).

  2. Path will not have whitespace characters.

Input Format

The only argument given is string A.
Output Format

Return a string denoting the simplified absolute path for a file (Unix-style).
For Example

Input 1:
    A = "/home/"
Output 1:
    "/home"

Input 2:
    A = "/a/./b/../../c/"
Output 2:
    "/c"
Method:

Use a stack to keep track of the path, then pop the stack from bottom

Solution:

Time: O(n)
Space: O(n)

public class Solution {
    public String simplifyPath(String A) {
        Deque<String> stack = new ArrayDeque<>();
        String[] arr = A.split("/");
        for (String c : arr) {
            if (c.equals("")) continue;
            if (c.equals(".")) continue;
            if (c.equals("..")) {
                if (!stack.isEmpty()) {
                    stack.pop();
                }
            } else {
                stack.push(c);
            }
        }
        StringBuilder sb = new StringBuilder();
        while (!stack.isEmpty()) {
            sb.append("/");
            sb.append(stack.pollLast());
        }
        if (sb.length() == 0) sb.append("/");
        return sb.toString();
    }
}