Definición de cola
La cola es una tabla lineal especial. La característica especial es que solo permite operaciones de eliminación en la parte delantera de la mesa y las inserciones en la parte posterior de la mesa. Al igual que la pila, la cola es una operación sujeta a operación. Tabla lineal de límites. El final de la operación de inserción se llama poner en cola y la operación de eliminar se llama sacar de cola.
Implementación de almacenamiento secuencial de la cola
package algorithm.datastructure.queue;
/*
* 队列
* 队列是一种特殊的线性表，特殊之处在于它只允许在表的前端（front）进行删除操作，
* 而在表的后端（rear）进行插入操作，和栈一样，队列是一种操作受限制的线性表。
* 进行插入操作的端称为入队，进行删除的操作成为出队
*
* 顺序队列:
* 采用连续的存储空间存储
*/
public class SeqQuque {
private int table[];//数组
private int front;//队首下标
private int rear;//队尾下标
private int maxSize;//队列的容量
private int length;//当前队列长度
private int incrementCapacity;//扩容时增长容量
private static final int QUEUE_DEFAULT_INIT_SIZE=10;//初始容量
private static final int QUEUE_DEFAULT_INCREMENT_SIZE=5;//扩容时默认增长容量
public SeqQuque(){
this.maxSize=QUEUE_DEFAULT_INIT_SIZE;
this.table=new int[maxSize];
this.front=this.rear=0;
this.incrementCapacity=QUEUE_DEFAULT_INCREMENT_SIZE;
}
public SeqQuque(int initialCapacity){
this.maxSize=initialCapacity;
this.table=new int[maxSize];
this.front=this.rear=0;
this.incrementCapacity=QUEUE_DEFAULT_INCREMENT_SIZE;
}
public SeqQuque(int initialCapacity,int incrementCapacity){
this.maxSize=initialCapacity;
this.table=new int[maxSize];
this.front=this.rear=0;
this.incrementCapacity=incrementCapacity;
}
//判断队列是否为空
public Boolean isEmpty(){
return front==rear;
}
//判断队列是否已满
public Boolean isFull(){
return length==maxSize;
}
//求队列长度
public int length(){
return length;
}
//表尾插入元素
public void enQueue(int x){
if (isFull()){
ensureCapacity();
table[rear++]=x;
length++;
} else{
table[rear++]=x;
length++;
}
}
//表头删除元素
public Integer deQueue(){
if (isEmpty()){
try {
throw new Exception("队列空");
} catch (Exception e) {
e.printStackTrace();
}
} else {
length--;
int x=table[front++];
return x;
}
return null;
}
//获取队头元素
public Integer getHead(){
if (isEmpty()){
try {
throw new Exception("队列空");
} catch (Exception e) {
e.printStackTrace();
}
} else {
return table[front];
}
return null;
}
//清空队列
public void clearQueue(){
this.maxSize=QUEUE_DEFAULT_INIT_SIZE;
this.table=new int[maxSize];
this.front=this.rear=0;
this.incrementCapacity=QUEUE_DEFAULT_INCREMENT_SIZE;
}
//扩容
private void ensureCapacity() {
System.out.println("当前队列的容量为:"+maxSize+"，容量不足，扩容");
maxSize=maxSize+incrementCapacity;
int []newTable=new int[maxSize];
for (int i=0;i<table.length;i++){
//将旧数组的元素移到新数组
newTable[i]=table[i];
}
table=newTable;
System.out.println("扩容成功，扩容后队列的新容量为:"+maxSize);
}
public static void main(String[] args) {
//测试
SeqQuque seqQuque=new SeqQuque(1,1);
seqQuque.enQueue(1);
seqQuque.enQueue(2);
seqQuque.enQueue(3);
System.out.println(seqQuque.length());
System.out.println(seqQuque.getHead());
System.out.println(seqQuque.getHead());
System.out.println(seqQuque.deQueue());
System.out.println(seqQuque.deQueue());
System.out.println(seqQuque.deQueue());
seqQuque.clearQueue();
//seqQuque.deQueue();
}
}
Implementación de almacenamiento en cadena de la cola
package algorithm.datastructure.queue;
/*
* 队列
* 队列是一种特殊的线性表，特殊之处在于它只允许在表的前端（front）进行删除操作，
* 而在表的后端（rear）进行插入操作，和栈一样，队列是一种操作受限制的线性表。
* 进行插入操作的端称为入队，进行删除的操作成为出队
* 顺序队列:
* 采用连非续的存储空间存储
*
*/
public class LinkedQueue {
private Node front;//队头指针
private Node rear;//队尾指针
private Integer length;//当前队列长度
private static class Node {
int data;
Node next;
public Node() {
}
public Node(int data) {
this.data = data;
this.next = null;
}
public Node(int data, Node next) {
this.data = data;
this.next = next;
}
}
//初始化
public LinkedQueue() {
front = new Node();
rear = front;
front.next = null;
length = 0;
}
//判断队列空
public Boolean isEmpty() {
return front == rear;
}
//队尾插入元素
public void enQueue(int x) {
Node newNode = new Node(x, null);
rear.next = newNode;
rear = newNode;
length++;
}
//队首删除元素
public Integer deQueue() {
if (isEmpty()) {
try {
throw new Exception("队列空");
} catch (Exception e) {
e.printStackTrace();
}
} else {
Node x = front.next;
front = front.next;
length--;
return x.data;
}
return null;
}
//获取队首元素
public Integer getHead() {
if (isEmpty()) {
try {
throw new Exception("队列空");
} catch (Exception e) {
e.printStackTrace();
}
} else {
return front.next.data;
}
return null;
}
//获取当前队列长度
public int length() {
return length;
}
//清空队列
public void clearQueue() {
front = new Node();
rear = front;
front.next = null;
length = 0;
}
public static void main(String[] args) {
//测试
LinkedQueue linkedQueue = new LinkedQueue();
//System.out.println(linkedQueue.deQueue());
linkedQueue.enQueue(6);
linkedQueue.enQueue(2);
linkedQueue.enQueue(3);
System.out.println(linkedQueue.length());
System.out.println(linkedQueue.getHead());
System.out.println(linkedQueue.deQueue());
System.out.println(linkedQueue.deQueue());
System.out.println(linkedQueue.deQueue());
//System.out.println(linkedQueue.deQueue());
linkedQueue.clearQueue();
}
}