DoubleLinkedList
DoubleLinkedList.java 源码
package datastructure.linkedlist;
/**
* @author roseduan[roseduan520@gmail.com]
* @date 2019/11/29 23:32
* @decription 双向链表的实现
*/
public class DoubleLinkedList {
private LisNode head;
public DoubleLinkedList(int val) {
this.head = new LisNode(val);
}
/**
* 链表节点
*/
private static class LisNode {
int val;
LisNode prev;
LisNode next;
LisNode(int val) {
this.val = val;
this.prev = null;
this.next = null;
}
}
/**
* 查找
*/
public LisNode find(int value){
LisNode p = head;
while (p != null && p.val != value){
p = p.next;
}
return p;
}
/**
* 插入
*/
public void add(int value) {
LisNode node = new LisNode(value);
if (head == null) {
head = node;
node.prev = head;
return;
}
LisNode p = head;
while (p.next != null){
p = p.next;
}
p.next = node;
node.prev = p;
}
/**
* 插入到链表头部
*/
public void addFirst(int value){
LisNode node = new LisNode(value);
if (head == null){
head = node;
node.prev = head;
return;
}
node.next = head;
head.prev = node;
head = node;
}
/**
* 在某个节点之前插入数据
*/
public void addBefore(LisNode p, int value){
if (p == null){
return;
}
if (p == head){
addFirst(value);
}
else {
LisNode node = new LisNode(value);
node.next = p;
p.prev.next = node;
node.prev = p.prev;
p.prev = node;
}
}
/**
* 删除数据
*/
public void remove(int value){
LisNode node = find(value);
if (node == null){
return;
}
//删除的是头节点
if (node == head){
head = head.next;
if (head != null){
head.prev = null;
}
}
else {
node.prev.next = node.next;
if (node.next != null){
node.next.prev = node.prev;
}
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
LisNode p = head;
while (p != null) {
sb.append(p.val).append(" ");
p = p.next;
}
return sb.toString();
}
}
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