class Node{ String value; Node next; Node(String s){ value = s; next = null; } } int n; Node head = null; if (str.length()==3){ Node ptr = head; if (head==null) sb.append("/\n"); while(ptr!=null){ sb.append("/"+ptr.value + "\n"); ptr = ptr.next; } } else{ str = str.subString(3,str.length()); if (str.charAt(0)=='/') head = null; String [] s = str.split("/"); for (int i=0; i<s.length; i++){ if (head==null){ head = new Node(s[i]); } else { Node ptr = head; while(ptr.next!=null) ptr = ptr.next; if (s.equals("..")) { ptr.next = null; } else { ptr.next = new Node(s[i]); } } } }