package com.bruce.homework0226;
import java.util.Objects;
public class LinkedListV01<T> {
private int size;
private Node<T> head;
private Node<T> last;
public LinkedListV01() {
//保证了初始化一个对象的时候,头节点不为空
this.head = new Node<T>(null);
}
public boolean add (T element) {
//双向链表,双向都需要维护
if(last == null){
last = new Node<>(element);
head.next = last;
last.pre = head;
}else{
Node<T> oldLast = last;
last = new Node<>(element);
last.pre = oldLast;
oldLast.next = last;
}
size++;
return true;
}
public boolean add(int index, T element) {
Node<T> node = getNode(index);
Node<T> newNode = new Node<T>(element);
Node<T> pre = node.pre;
pre.next = newNode;
newNode.pre = pre;
newNode.next = node;
size++;
return true;
}
public boolean remove(T element){
Node<T> node = head;
//下一个节点不为null
while(node.next != null){
node = node.next;
if(Objects.equals(node.element, element)){
if(node.next != null){
node.next.pre = node.pre;
}
node.pre.next = node.next;
size--;
return true;
}
}
//下一个节点为null,说明是尾节点
if(node != head){
last = node;
}
//head.next=null,说明是一个空的链表,即仅有一个空head节点
return false;
}
public T remove(int index){
Node<T> node = getNode(index);
Node<T> pre = node.pre;
Node<T> next = node.next;
pre.next = next;
next.pre = pre;
size--;
return node.element;
}
public void clear(){
for(Node<T> x = head; x != null; ){
Node<T> next = x.next;
x.pre = null;
x.next = null;
x.element = null;
}
head = last = null;
size = 0;
}
public int size(){
return size;
}
public boolean isEmpty(){
return size == 0;
}
public boolean contains(Object o){
for(int i = 0; i < size; i++){
if(Objects.equals(getNode(i).element, o)){
return true;
}
}
return false;
}
public Node<T> getNode(int index){
if(index < 0 || index >size){
return null;
}
Node<T> node = head;
for(int i = 0; i < index; i++){
node = node.next;
}
return node;
}
public T get(int index) {
return getNode(index).element;
}
public int indexOf(T element){
Node<T> node = head;
int index = 0;
while(node.next != null){
node = node.next;
if(Objects.equals(node.element, element)){
return index;
}
index++;
}
return -1;
}
private static class Node<T> {
T element;
Node<T> pre;
Node<T> next;
Node(T element) {
this.element = element;
}
}
}