public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter string to be converted into char linked list");
String input = sc.next();
LinkedList list = new LinkedList();
for (char i : input.toCharArray()) {
list.addElementAtEnd(new Character(i));
}
LinkedList list1 = list.clone();
System.out.print("Remove Dups with Buffer space : ");
removeDupsWithBuffer(list1).display();
LinkedList list2 = list.clone();
System.out.print("Remove Dups without Buffer space : ");
removeDupsWithoutBuffer(list2).display();
sc.close();
}
/**
* Uses HashSet as the extra storage space
*
* @param list
* @return
*/
public static LinkedList removeDupsWithBuffer(LinkedList list) {
HashSet<Object> bufferHash = new HashSet<Object>();
Node current = list.getFirst();
Node previous = null;
while (current != null) {
// If Hashset contains the element, delete the current element
// Else add to the hashset and move forward
if (bufferHash.contains(current.getData())) {
previous.setNext(current.getNext());
} else {
bufferHash.add(current.getData());
previous = current;
}
current = current.getNext();
}
return list;
}
/**
* Does not use any buffer space
*
* @param list
* @return
*/
public static LinkedList removeDupsWithoutBuffer(LinkedList list) {
if (list == null) return null;
Node current = list.getFirst();
// Iterate over the linkedlist
// Run an iterator from the current node to delete any duplicate values
while (current != null) {
Node iterator = current;
while (iterator.getNext() != null) {
if (iterator.getNext().getData().equals(current.getData())) {
iterator.setNext(iterator.getNext().getNext());
} else {
iterator = iterator.getNext();
}
}
current = current.getNext();
}
return list;
}