手写单链表，实现增删改查

package top.zcwfeng.java.arithmetic.lru;

//单链表

public class LinkedList {

Node list;

int size;//链表节点个数

public LinkedList() {

}

// 添加

public void put(T data) {

Node head = list;//保存一下

Node currentNode = new Node(data,list);

list = currentNode;

size ++;

}

public void put(int index, T data) {

checkPositonIndex(index);

Node cur = list;

Node head = list;// 保存当前的节点前面的节点

for (int i = 0; i < index; i++) {

head = cur;

cur = cur.next;

}

Node node = new Node(data,cur);

head.next = node;

size++;

}

/**

* 检查index 是否在链表的范围内

* @param index

*/

public void checkPositonIndex(int index) {

if(!(index >= 0 && index <= size)){

throw new IndexOutOfBoundsException("index:" + index + ",size:"+size);

}

}

// 修改

public void set(int index, T newData) {

checkPositonIndex(index);

Node head = list;// 保存当前的节点前面的节点

for (int i = 0; i < index; i++) {

head = head.next;

}

head.data = newData;

}

// 删除

/**

* 删除头部

*

* @return

*/

public T remove() {

if(list != null){

Node node = list;

list = list.next;

node.next = null;

size--;

return node.data;

}

return null;

}

public T remove(int index) {

checkPositonIndex(index);

Node head = list;

Node cur = list;

for (int i = 0; i < index; i++) {

head = cur;

cur = cur.next;

}

head.next = cur.next;

cur.next = null;

size--;

return cur.data;

}

public T removeLast() {

if(list != null){

Node node = list;

Node cur = list;

while (cur.next != null){

node = cur;

cur = cur.next;

}

node.next = null;

size --;

return cur.data;

}

return null;

}

// 查询

/**

* get head

*

* @return

*/

public T get() {

Node node = list;

if(node != null){

return list.data;

} else {

return null;

}

}

public T get(int index) {

checkPositonIndex(index);

Node node = list;

for (int i = 0; i < index; i++) {

node = node.next;

}

return node.data;

}

@Override

public String toString() {

Node node = list;

for (int i = 0; i < size; i++) {

System.out.println(node.data + " ");

node = node.next;

}

System.out.println();

return super.toString();

}

// 节点信息

class Node {

T data;

Node next;

public Node(T data, Node next) {

this.data = data;

this.next = next;

}

}

public static void main(String[] args) {

LinkedList list = new LinkedList<>();

for (int i = 0; i < 5; i++) {

list.put(i);

}

list.toString();

list.put(3,3);

list.toString();

list.put(8);

list.toString();

}

}

根据单链表操作，实现LRU算法

新数据插入到链表头部

当缓存命中(即缓存数据被访问)，数据要移到表头

当链表满的时候，将链表尾部的数据丢弃

package top.zcwfeng.java.arithmetic.lru;

public class LruLinkedList extends LinkedList {

static final int DEFAULT_CAP = 5;

int memeory_size;//用于限定内存大小，也就是缓存大小

public LruLinkedList() {

this(DEFAULT_CAP);

}

public LruLinkedList(int memeory_size) {

this.memeory_size = memeory_size;

}

public void lruPut(T data) {

if(size >= memeory_size){

removeLast();

put(data);

}else{

put(data);

}

}

public T lruRemove(){

return removeLast();

}

public T lruGet(int index){

checkPositonIndex(index);

Node node = list;

Node pre = list;

for (int i = 0; i < index; i++) {

pre = node;

node = node.next;

}

T resultData = node.data;

// 将访问节点放到表头

pre.next = node.next;

Node head = list;

node.next = head;

list = node;

return resultData;

}

public static void main(String[] args) {

LruLinkedList lruLinkedList = new LruLinkedList<>();

for (int i = 0; i < 4; i++) {

lruLinkedList.lruPut(i);

}

lruLinkedList.toString();

System.out.println(lruLinkedList.lruGet(3));

lruLinkedList.toString();

lruLinkedList.lruPut(20);

lruLinkedList.toString();

lruLinkedList.lruPut(18);

lruLinkedList.toString();

}

}

给LinkeList 添加翻转单链表方法

public void reverse(){

//单链表为空或只有一个节点，直接返回原单链表

if (list == null || list.next == null){

return;

}

Node head = list;

Node next = list.next;

list.next = null;

Node temp;

while(next !=null){

temp = next.next;

next.next = head;

head = next;

next = temp;

}

list = head;

}