public boolean insertAfter(int data, int k) { // insert data after DNode w/data k
if (head == null) {
return false;
}
DNode current = head;
while (current.getData() != k) {
current = current.getNext();
if (current == null) {
return false; // didn't find k
}
}
// insert after current Node
DNode insertingNode = new DNode(data);
if (current.getNext() == null) { // is current the last Node?
current.setNext(insertingNode);
insertingNode.setPrev(current);
return true;
}
// not at last node
DNode temp = current.getNext();
current.setNext(insertingNode);
insertingNode.setPrev(current);
insertingNode.setNext(temp);
temp.setPrev(insertingNode);
// example:
// if we are inserting after 2
// 1<->2<->4<->5<->6
// insertingNode = 3
// temp = 4
// in order: 2->3, 2<->3, 2<->3->4, 2<->3<->4, result: //1<->2<->3<->4<->5<->6
return true;
}
public boolean delete(int data) {
boolean isDeleted = false;
if (head.getData() == data) {
head.setNext(head);
head.setPrev(null);
isDeleted = true;
return isDeleted;
}
DNode current = head;
// 1 <-> 2 <-> 3 <-> 4 <-> 5
while (current.getNext() != null) {
if (current.getNext().getData() == data) {
current.setNext(current.getNext().getNext());
current.getNext().setPrev(current);
isDeleted = true;
}
current = current.getNext();
}
return isDeleted;
}
public void insertAtEnd(int data) {
DNode insertingNode = new DNode(data);
if (head == null) {
head = insertingNode;
} else {
DNode current = head;
while (current.getNext() != null) {
current = current.getNext();
}
current.setNext(insertingNode);
insertingNode.setPrev(current);
}
}
