package offer;

//在 O(1)时间删除链表结点

public class Problem13 {

    public static void main(String[] args) {

        ListNode node1 = new ListNode();

        ListNode node2 = new ListNode();

        ListNode node3 = new ListNode();

        ListNode node4 = new ListNode();

        node1.nextNode = node2;

        node2.nextNode = node3;

        node3.nextNode = node4;

        node1.value = 1;

        node2.value = 2;

        node3.value = 3;

        node4.value = 4;

        System.out.println(node1.value);

        System.out.println(node2.value);

        System.out.println(node3.value);

        System.out.println(node4.value);

        //deleteNode(node1, node3);

        //deleteNode(node1, node1);

        //deleteNode(node1, node2);

        //deleteNode(node1, node4);

        deleteNode(node1, null);

        System.out.println(node1.value);

        System.out.println(node1.nextNode.value);

        System.out.println(node1.nextNode.nextNode.value);

        //System.out.println(node4.value);

    }

    public static void deleteNode(ListNode head,ListNode deleteNode){

        if(head == null || deleteNode == null)return;

        if(deleteNode == head && head.nextNode == null)//delete head

        {

            head = null;

        }else

        {

            if(deleteNode.nextNode == null)

            {//delete tail，traverse loop

                ListNode temp = head;

                while(temp.nextNode.nextNode != null)

                {

                    temp = temp.nextNode;

                }

                temp.nextNode = null;

            }

            else

            {

                deleteNode.value = deleteNode.nextNode.value;

                deleteNode.nextNode = deleteNode.nextNode.nextNode;

            }

        }

    }

}