在单链表和双链表中删除倒数第k个节点

//在单链表和双链表中删除倒数第k个节点

public class DeleteList{

//单链表节点的定义
public static class Node{
int value;
Node next;

public Node(int data)
{
this.value=data;
}

}

//删除单链表中倒数第k个节点
public static int DeletList_K(Node head,int k)
{
Node t=head; //用t指向链表的头结点
if(head==null||k<1)
{
return -10000;  //表示没有删除的数据
}
int leng=0; //计算链表的长度
while(t!=null)
{
t=t.next;
++leng;
}
//System.out.println(leng); 打印出链表的长度为3
if(k>leng)
{
return -10000;  //表示没有删除的数据
}
for(int i=0;i<leng-k-1;i++)
{
head=head.next;  //找到倒数第k-1个节点
}
Node p=head.next;  //找到倒数第k个节点
head.next=head.next.next; //删除倒数第k个节点
return p.value;
}

//双链表节点的定义
public static class Node2{
int value;
Node2 next,pre;

public Node2(int data)
{
this.value=data;
}

}
//删除双链表中倒数第k个节点
public static int DelteTwoList_K(Node2 head2,int k)
{
Node2 t=head2; //用t指向链表的头结点
if(head2==null||k<1)
{

return -10000;
}
int leng=0; //计算双链表的长度
while(t!=null)
{
t=t.next;
++leng;
}
//System.out.println(leng); //打印出链表的长度为3
if(k>leng)
{
return -10000;  //表示没有删除的数据
}

for(int i=0;i<leng-k;i++)
{
head2=head2.next;
}
Node2 p=head2; //倒数第k个节点

p.pre.next=p.next;  //删除倒数第k个节点

return p.value;

}

public static void main(String []args)
{
//删除单链表倒数第k个节点测试  链表为 1->2->3
Node node=new Node(1);
node.next=new Node(2);
node.next.next=new Node(3);
//node.next.next.next=new Node(4);
System.out.println(DeletList_K(node,2));

//删除双链表倒数第k个节点测试  链表为 1->2->3
Node2 node2=new Node2(1);
node2.next=new Node2(2);
node2.next.next=new Node2(3);
node2.next.pre=node2;
node2.next.next.pre=node2.next;
//node.next.next.next=new Node(4);
System.out.println(DelteTwoList_K(node2,2));

}
}

public class Problem_02_RemoveLastKthNode {

public static class Node {
public int value;
public Node next;

public Node(int data) {
this.value = data;
}
}

public static Node removeLastKthNode(Node head, int lastKth) {
if (head == null || lastKth < 1) {
return head;
}
Node cur = head;
while (cur != null) {
lastKth--;
cur = cur.next;
}
if (lastKth == 0) {
head = head.next;
}
if (lastKth < 0) {
cur = head;
while (++lastKth != 0) {
cur = cur.next;
}
cur.next = cur.next.next;
}
return head;
}

public static class DoubleNode {
public int value;
public DoubleNode last;
public DoubleNode next;

public DoubleNode(int data) {
this.value = data;
}
}

public static DoubleNode removeLastKthNode(DoubleNode head, int lastKth) {
if (head == null || lastKth < 1) {
return head;
}
DoubleNode cur = head;
while (cur != null) {
lastKth--;
cur = cur.next;
}
if (lastKth == 0) {
head = head.next;
head.last = null;
}
if (lastKth < 0) {
cur = head;
while (++lastKth != 0) {
cur = cur.next;
}
DoubleNode newNext = cur.next.next;
cur.next = newNext;
if (newNext != null) {
newNext.last = cur;
}
}
return head;
}

public static void printLinkedList(Node head) {
System.out.print("Linked List: ");
while (head != null) {
System.out.print(head.value + " ");
head = head.next;
}
System.out.println();
}

public static void printDoubleLinkedList(DoubleNode head) {
System.out.print("Double Linked List: ");
DoubleNode end = null;
while (head != null) {
System.out.print(head.value + " ");
end = head;
head = head.next;
}
System.out.print("| ");
while (end != null) {
System.out.print(end.value + " ");
end = end.last;
}
System.out.println();
}

public static void main(String[] args) {
Node head1 = new Node(1);
head1.next = new Node(2);
head1.next.next = new Node(3);
head1.next.next.next = new Node(4);
head1.next.next.next.next = new Node(5);
head1.next.next.next.next.next = new Node(6);
printLinkedList(head1);
head1 = removeLastKthNode(head1, 3);
// head1 = removeLastKthNode(head1, 6);
// head1 = removeLastKthNode(head1, 7);
printLinkedList(head1);

DoubleNode head2 = new DoubleNode(1);
head2.next = new DoubleNode(2);
head2.next.last = head2;
head2.next.next = new DoubleNode(3);
head2.next.next.last = head2.next;
head2.next.next.next = new DoubleNode(4);
head2.next.next.next.last = head2.next.next;
head2.next.next.next.next = new DoubleNode(5);
head2.next.next.next.next.last = head2.next.next.next;
head2.next.next.next.next.next = new DoubleNode(6);
head2.next.next.next.next.next.last = head2.next.next.next.next;
printDoubleLinkedList(head2);
head2 = removeLastKthNode(head2, 3);
// head2 = removeLastKthNode(head2, 6);
// head2 = removeLastKthNode(head2, 7);
printDoubleLinkedList(head2);

}

}