이중 연결리스트

더블 링크드 리스트

• 양방향으로 연결이 되어있기 때문에 노드의 탐색이 양쪽(전, 후)으로 가능하다.

public class MyDoubleLinkedList<T> {

    public Node<T> head = null;
    public Node<T> tail = null;

    public class Node<T> {
        T data;
        Node<T> prev = null;
        Node<T> next = null;

        public Node(T data) {
            this.data = data;
        }
    }

    public void addInsideNode(T data,T isData) {
        if(this.head == null) {
            addNode(data);
        } else if (this.head.data == isData) {
            Node<T> newHead = new Node<>(data);
            newHead.next = this.head;
            this.head = newHead;
        } else {
            Node<T> node = this.head;
            while (node != null) {

                if (node.data == isData) {

                    Node<T> prevNode = node.prev;
                    prevNode.next = new Node<>(data);
                    prevNode.next.next = node;
                    prevNode.next.prev = prevNode;
                    node.prev = prevNode.next;
                    break;
                }
                node = node.next;
            }
        }
    }

    public void addNode(T data) {
        if (this.head == null) {
            this.head = new Node<>(data);
            this.tail = this.head;
        } else {
            Node<T> node = this.head;
            while (node.next != null) {
                node = node.next;
            }
            node.next = new Node<>(data);
            node.next.prev = node;
            this.tail = node.next;
        }
    }

    public void printAll() {
        if (this.head != null) {
            Node<T> node = this.head;
            System.out.println(node.data);
            while (node.next != null) {
                node = node.next;
                System.out.println(node.data);
            }
        }
    }

    private T searchFromHead(T isData) {
        if (this.head == null) {
            return null;
        } else {
            Node<T> node = this.head;
            while (node != null) {
                if (node.data == isData) {
                    return node.data;
                } else {
                    node = node.next;
                }
            }
            return null;
        }
    }

    public T searchFromTail(T isData) {
        if (this.head == null) {
            return null;
        } else {
            Node<T> node = this.tail;
            while (node != null) {
                if (node.data == isData) {
                    return node.data;
                } else {
                    node = node.prev;
                }
            }
            return null;
        }
    }

    public static void main(String[] args) {
        MyDoubleLinkedList<Integer> myDoubleLinkedList = new MyDoubleLinkedList<>();

        myDoubleLinkedList.addNode(1);
        myDoubleLinkedList.addNode(3);
        myDoubleLinkedList.addNode(5);
        myDoubleLinkedList.addNode(7);
        myDoubleLinkedList.addNode(9);
        myDoubleLinkedList.addInsideNode(6, 7);

        myDoubleLinkedList.printAll();


    }

}