1.隊列的順序存儲結構及實現
public class SequenceQueue<T>
{
private int DEFAULT_SIZE = 10;
//保存數組的長度。
private int capacity;
//定義一個數組用於保存順序隊列的元素
private Object[] elementData;
//保存順序隊列中元素的當前個數
private int front = 0;
private int rear = 0;
//以默認數組長度創建空順序隊列
public SequenceQueue()
{
capacity = DEFAULT_SIZE;
elementData = new Object[capacity];
}
//以一個初始化元素來創建順序隊列
public SequenceQueue(T element)
{
this();
elementData[0] = element;
rear++;
}
/**
* 以指定長度的數組來創建順序隊列
* @param element 指定順序隊列中第一個元素
* @param initSize 指定順序隊列底層數組的長度
*/
public SequenceQueue(T element , int initSize)
{
this.capacity = initSize;
elementData = new Object[capacity];
elementData[0] = element;
rear++;
}
//獲取順序隊列的大小
public int length()
{
return rear - front;
}
//插入隊列
public void add(T element)
{
if (rear > capacity - 1)
{
throw new IndexOutOfBoundsException("隊列已滿的異常");
}
elementData[rear++] = element;
}
//移除隊列
public T remove()
{
if (empty())
{
throw new IndexOutOfBoundsException("空隊列異常");
}
//保留隊列的rear端的元素的值
T oldValue = (T)elementData[front];
//釋放隊列的rear端的元素
elementData[front++] = null;
return oldValue;
}
//返回隊列頂元素，但不刪除隊列頂元素
public T element()
{
if (empty())
{
throw new IndexOutOfBoundsException("空隊列異常");
}
return (T)elementData[front];
}
//判斷順序隊列是否爲空隊列
public boolean empty()
{
return rear == front;
}
//清空順序隊列
public void clear()
{
//將底層數組所有元素賦爲null
Arrays.fill(elementData , null);
front = 0;
rear = 0;
}
public String toString()
{
if (empty())
{
return "[]";
}
else
{
StringBuilder sb = new StringBuilder("[");
for (int i = front ; i < rear ; i++ )
{
sb.append(elementData[i].toString() + ", ");
}
int len = sb.length();
return sb.delete(len - 2 , len).append("]").toString();
}
}
}
import java.util.Arrays;
public class LoopQueue<T>
{
private int DEFAULT_SIZE = 10;
//保存數組的長度。
private int capacity;
//定義一個數組用於保存循環隊列的元素
private Object[] elementData;
//保存循環隊列中元素的當前個數
private int front = 0;
private int rear = 0;
//以默認數組長度創建空循環隊列
public LoopQueue()
{
capacity = DEFAULT_SIZE;
elementData = new Object[capacity];
}
//以一個初始化元素來創建循環隊列
public LoopQueue(T element)
{
this();
elementData[0] = element;
rear++;
}
/**
* 以指定長度的數組來創建循環隊列
* @param element 指定循環隊列中第一個元素
* @param initSize 指定循環隊列底層數組的長度
*/
public LoopQueue(T element , int initSize)
{
this.capacity = initSize;
elementData = new Object[capacity];
elementData[0] = element;
rear++;
}
//獲取循環隊列的大小
public int length()
{
if (empty())
{
return 0;
}
return rear > front ? rear - front
: capacity - (front - rear);
}
//插入隊列
public void add(T element)
{
if (rear == front
&& elementData[front] != null)
{
throw new IndexOutOfBoundsException("隊列已滿的異常");
}
elementData[rear++] = element;
//如果rear已經到頭，那就轉頭
rear = rear == capacity ? 0 : rear;
}
//移除隊列
public T remove()
{
if (empty())
{
throw new IndexOutOfBoundsException("空隊列異常");
}
//保留隊列的rear端的元素的值
T oldValue = (T)elementData[front];
//釋放隊列的rear端的元素
elementData[front++] = null;
//如果front已經到頭，那就轉頭
front = front == capacity ? 0 : front;
return oldValue;
}
//返回隊列頂元素，但不刪除隊列頂元素
public T element()
{
if (empty())
{
throw new IndexOutOfBoundsException("空隊列異常");
}
return (T)elementData[front];
}
//判斷循環隊列是否爲空隊列
public boolean empty()
{
//rear==front且rear處的元素爲null
return rear == front
&& elementData[rear] == null;
}
//清空循環隊列
public void clear()
{
//將底層數組所有元素賦爲null
Arrays.fill(elementData , null);
front = 0;
rear = 0;
}
public String toString()
{
if (empty())
{
return "[]";
}
else
{
//如果front < rear，有效元素就是front到rear之間的元素
if (front < rear)
{
StringBuilder sb = new StringBuilder("[");
for (int i = front ; i < rear ; i++ )
{
sb.append(elementData[i].toString() + ", ");
}
int len = sb.length();
return sb.delete(len - 2 , len).append("]").toString();
}
//如果front >= rear，有效元素爲front->capacity之間、0->front之間的
else
{
StringBuilder sb = new StringBuilder("[");
for (int i = front ; i < capacity ; i++ )
{
sb.append(elementData[i].toString() + ", ");
}
for (int i = 0 ; i < rear ; i++)
{
sb.append(elementData[i].toString() + ", ");
}
int len = sb.length();
return sb.delete(len - 2 , len).append("]").toString();
}
}
}
}
public class LinkQueue<T>
{
//定義一個內部類Node，Node實例代表鏈隊列的節點。
private class Node
{
//保存節點的數據
private T data;
//指向下個節點的引用
private Node next;
//無參數的構造器
public Node()
{
}
//初始化全部屬性的構造器
public Node(T data , Node next)
{
this.data = data;
this.next = next;
}
}
//保存該鏈隊列的頭節點
private Node front;
//保存該鏈隊列的尾節點
private Node rear;
//保存該鏈隊列中已包含的節點數
private int size;
//創建空鏈隊列
public LinkQueue()
{
//空鏈隊列，front和rear都是null
front = null;
rear = null;
}
//以指定數據元素來創建鏈隊列，該鏈隊列只有一個元素
public LinkQueue(T element)
{
front = new Node(element , null);
//只有一個節點，front、rear都指向該節點
rear = front;
size++;
}
//返回鏈隊列的長度
public int length()
{
return size;
}
//將新元素加入隊列
public void add(T element)
{
//如果該鏈隊列還是空鏈隊列
if (front == null)
{
front = new Node(element , null);
//只有一個節點，front、rear都指向該節點
rear = front;
}
else
{
//創建新節點
Node newNode = new Node(element , null);
//讓尾節點的next指向新增的節點
rear.next = newNode;
//以新節點作爲新的尾節點
rear = newNode;
}
size++;
}
//刪除隊列front端的元素
public T remove()
{
Node oldFront = front;
front = front.next;
oldFront.next = null;
size--;
return oldFront.data;
}
//訪問鏈式隊列中最後一個元素
public T element()
{
return rear.data;
}
//判斷鏈式隊列是否爲空隊列
public boolean empty()
{
return size == 0;
}
//清空鏈隊列
public void clear()
{
//將front、rear兩個節點賦爲null
front = null;
rear = null;
size = 0;
}
public String toString()
{
//鏈隊列爲空鏈隊列時
if (empty())
{
return "[]";
}
else
{
StringBuilder sb = new StringBuilder("[");
for (Node current = front ; current != null
; current = current.next )
{
sb.append(current.data.toString() + ", ");
}
int len = sb.length();
return sb.delete(len - 2 , len).append("]").toString();
}
}
}