Java數據結構之鏈表相關知識總結
一、鏈表
1.1 概述
鏈表是真正動態的數據結構，最簡單的動態數據結構，基本用於輔助組成其他數據結構。
數據存儲在“節點”（Node）中
優點：真正的動態，不需要處理固定容量的問題
缺點：喪失瞭隨機訪問的能力
1.2 鏈表使用的基本功能
定義Node節點
private class Node{
public E e;
public Node next;
public Node(E e, Node next){
this.e = e;
this.next = next;
}
public Node(E e){
this(e, null);
}
public Node(){
this(null,null);
}
@Override
public String toString() {
return e.toString();
}
}
向鏈表中添加元素
具體代碼實現：
//向鏈表中間添加元素
//在鏈表的index(0-based)位置添加新的元素e
public void add(int index, E e){
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed.Illeagl failed.");
Node prev = dummyHead;
for (int i = 0; i < index; i++) {
prev = prev.next;
}
// Node node = new Node(e);
// node.next = prev.next;
// prev.next = node;
prev.next = new Node(e, prev.next);
size++;
}
向鏈表中刪除元素
具體代碼實現：
//鏈表中刪除index(0-based)位置的元素，返回刪除的元素
public E remove(int index){
if(index < 0 || index >= size)
throw new IllegalArgumentException("Remove failed.Illeagl failed.");
Node pre = dummyHead;
for (int i = 0; i < index; i++) {
pre = pre.next;
}
Node retNode = pre.next;
pre.next = retNode.next;
retNode.next = null;
size--;
return retNode.e;
}
鏈表功能的實現及測試類
public class LinkedList<E> {
private class Node{
public E e;
public Node next;
public Node(E e, Node next){
this.e = e;
this.next = next;
}
public Node(E e){
this(e, null);
}
public Node(){
this(null,null);
}
@Override
public String toString() {
return e.toString();
}
}
private Node dummyHead;
private int size;
public LinkedList(){
dummyHead = new Node(null, null);
size = 0;
}
//獲取鏈表中的元素個數
public int getSize(){
return size;
}
//返回鏈表是否為空
public boolean isEmpty(){
return size == 0;
}
//向鏈表頭添加元素
public void addFirst(E e){
// Node node = new Node(e);
// node.next = head;
// head = node;
add(0, e);
}
//向鏈表中間添加元素
//在鏈表的index(0-based)位置添加新的元素e
public void add(int index, E e){
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed.Illeagl failed.");
Node prev = dummyHead;
for (int i = 0; i < index; i++) {
prev = prev.next;
}
// Node node = new Node(e);
// node.next = prev.next;
// prev.next = node;
prev.next = new Node(e, prev.next);
size++;
}
//在鏈表的末尾添加新的元素e
public void addLast(E e){
add(size, e);
}
//獲得鏈表的第index(0-based)個位置的元素
//在鏈表中不是一個常用的操作
public E get(int index){
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed.Illeagl failed.");
Node cur = dummyHead.next;
for (int i = 0; i < index; i++) {
cur = cur.next;
}
return cur.e;
}
//獲得鏈表的第一個元素
public E getFirst(){
return get(0);
}
//獲得鏈表的最後一個元素
public E getLast(){
return get(size - 1);
}
//修改鏈表的第index(0-based)個位置的元素
//在鏈表中不是一個常用的操作
public void set(int index, E e){
if(index < 0 || index > size)
throw new IllegalArgumentException("Add failed.Illeagl failed.");
Node cur = dummyHead.next;
for (int i = 0; i < index; i++) {
cur = cur.next;
}
cur.e = e;
}
//查找鏈表中是否有元素e
public boolean contains(E e){
Node cur = dummyHead.next;
while(cur != null){
if(cur.e.equals(e)){
return true;
}
cur = cur.next;
}
return false;
}
//鏈表中刪除index(0-based)位置的元素，返回刪除的元素
public E remove(int index){
if(index < 0 || index >= size)
throw new IllegalArgumentException("Remove failed.Illeagl failed.");
Node pre = dummyHead;
for (int i = 0; i < index; i++) {
pre = pre.next;
}
Node retNode = pre.next;
pre.next = retNode.next;
retNode.next = null;
size--;
return retNode.e;
}
//從鏈表中刪除第一個元素
public E removeFirst(){
return remove(0);
}
//從鏈表中刪除最後一個元素
public E removeLast(){
return remove(size - 1);
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
// Node cur = dummyHead.next;
// while (cur != null){
// res.append(cur + "->");
// cur = cur.next;
// }
for (Node cur = dummyHead.next; cur != null; cur = cur.next){
res.append(cur + "->");
}
res.append("null");
return res.toString();
}
public static void main(String[] args) {
LinkedList<Integer> linkedList = new LinkedList<>();
for (int i = 0; i < 5; i++) {
linkedList.addFirst(i);
System.out.println(linkedList);
}
linkedList.add(2, 666);
System.out.println(linkedList);
linkedList.remove(2);
System.out.println(linkedList);
linkedList.removeFirst();
System.out.println(linkedList);
linkedList.removeLast();
System.out.println(linkedList);
}
}
二、鏈表實現棧操作
使用第二章中的棧接口，創建第一節中的鏈表實現對象，實現棧的操作，具體如下：
public class LinkedListStack<E> implements Stack<E> {
private LinkedList<E> list;
public LinkedListStack(){
list = new LinkedList<>();
}
@Override
public int getSize() {
return list.getSize();
}
@Override
public boolean isEmpty() {
return list.isEmpty();
}
@Override
public void push(E value) {
list.addFirst(value);
}
@Override
public E pop() {
return list.removeFirst();
}
@Override
public E peek() {
return list.getFirst();
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append("Stack : top");
res.append(list);
return res.toString();
}
public static void main(String[] args) {
LinkedListStack<Integer> stack = new LinkedListStack<>();
for (int i = 0; i < 5; i++) {
stack.push(i);
System.out.println(stack);
}
stack.pop();
System.out.println(stack);
}
}
三、鏈表實現隊列操作
使用第二章中的隊列接口，創建無頭節點的鏈表實現隊列操作，具體如下：
public class LinkedListQueue<E> implements Queue<E> {
private class Node{
public E e;
public LinkedListQueue.Node next;
public Node(E e, LinkedListQueue.Node next){
this.e = e;
this.next = next;
}
public Node(E e){
this(e, null);
}
public Node(){
this(null,null);
}
@Override
public String toString() {
return e.toString();
}
}
private Node head,tail;
private int size;
public LinkedListQueue(){
head = null;
tail = null;
size = 0;
}
@Override
public int getSize() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
public void enqueue(E e) {
if(tail == null){
tail = new Node(e);
head = tail;
}else{
tail.next = new Node(e);
tail = tail.next;
}
size++;
}
@Override
public E dequeue() {
if (isEmpty())
throw new IllegalArgumentException("Cannot dequeue form any empty queue.");
Node retNode = head;
head = head.next;
retNode.next = null;
if (head == null)
tail = null;
return retNode.e;
}
@Override
public E getFront() {
if (isEmpty())
throw new IllegalArgumentException("Cannot getFront form any empty queue.");
return head.e;
}
@Override
public String toString() {
StringBuilder res = new StringBuilder();
res.append("Queue : front ");
Node cur = head;
while (cur != null){
res.append(cur + "->");
cur = cur.next;
}
res.append("Null tail");
return res.toString();
}
public static void main(String[] args) {
LinkedListQueue<Integer> queue = new LinkedListQueue<>();
for (int i = 0; i < 10; i++) {
queue.enqueue(i);
System.out.println(queue);
if(i % 3 == 2){
queue.dequeue();
System.out.println(queue);
}
}
}
}
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