Java数据结构和算法--栈与队列

(1)栈

package ChapterOne;

public class Stack {
	//栈数组
	long stackArr[];
	//栈的大小
	int maxSize;
	//栈的顶部
	int top;
	//初始化一个大小为size的栈
	public Stack(int size){
		maxSize = size; 
		stackArr = new long[size];
		top = -1;
	}
	//出栈操作
	public long pop(){
		return stackArr[top--];
	}
	//进栈操作
	public void push(long value){
		stackArr[++top] = value;
	}
	//判断栈是否为空
	public boolean isEmpty(){
		return top == -1;
	}
	//判断栈是否已满
	public boolean isFull(){
		return top == maxSize-1;
	}
	//取栈顶元素
	public long peek(){
		return stackArr[top];
	}
	public static void main(String[] args) {
		Stack stack = new Stack(10);
		while(!stack.isFull()){
			long v = (long) (Math.random()*100);
			stack.push(v);
			System.out.print(v+" ");
		}
		System.out.println();
		while(!stack.isEmpty()){
			long topValue = stack.pop();
			System.out.print(topValue+" ");
		}
		System.out.println();
	}
}

(2)队列

package ChapterOne;

public class Queue {
	//队列数组
	private long queueArr[];
	//队列的前端下标
	private int front;
	//队列的尾端下标
	private int rear;
	//队列的大小
	private int maxSize;
	//队列中元素的个数
	private int nItems;
	//初始化一个大小为size的队列
	public Queue(int size){
		queueArr = new long[size];
		maxSize = size;
		front = 0;
		rear = -1;
		nItems = 0;
	}
	//插入操作
	public void insert(long value){
		//队列已满
		if(rear == maxSize-1)
			rear = -1;
		queueArr[++rear] = value;
		nItems++;
	}
	//删除操作
	public long remove(){
		long temp = queueArr[front++];
		if(front == maxSize)
			front = 0;
		nItems--;
		return temp;
	}
	//返回队列第一个元素
	public long peakFront(){
		return queueArr[front];
	}
	//判断是否为空
	public boolean isEmpty(){
		return nItems == 0;
	}
	//判断是否已满
	public boolean isFull(){
		return nItems == maxSize;
	}
	//返回队列中元素的个数
	public int size(){
		return nItems;
	}
	
	public void print(){
		for(int i = front;i < front+nItems;i++){
			System.out.print(queueArr[i]+" ");
		}
		System.out.println();
	}
	
	public static void main(String[] args) {
		Queue q = new Queue(10);
		while(!q.isFull()){
			long value = (long)(Math.random()*100);
			q.insert(value);
		}
		q.print();
		while(!q.isEmpty()){
			q.remove();
			q.print();
		}
		q.print();
		System.out.println(q.isEmpty());
	}
}

(3)优先队列

package ChapterOne;

public class PriorityQueue {

	private int nItems;
	
	private long pqArr[];
	
	private int maxSize;
	
	public PriorityQueue(int size){
		maxSize = size;
		pqArr = new long[size];
		nItems = 0;
	}
	
	public void insert(long value){
		int i;
		if(nItems == 0)
			pqArr[nItems++] = value;
		else{
			for(i = nItems-1;i >= 0;i--){
				if(value < pqArr[i]){
					pqArr[i+1] = pqArr[i];
				}
				else
					break;
			}
			pqArr[i+1] = value;
			nItems++;
		}
	}
	
	public long remove(){
		return pqArr[--nItems];
	}
	
	public boolean isEmpty(){
		return nItems == 0;
	}
	
	public boolean isFull(){
		return nItems == maxSize;
	}
	
	public void print(){
		for(int i = 0;i < nItems;i++)
			System.out.print(pqArr[i]+" ");
		System.out.println();
	}
	
	public static void main(String[] args) {
		PriorityQueue pq = new PriorityQueue(10);
		while(!pq.isFull()){
			long value = (long)(Math.random()*100);
			pq.insert(value);
		}
		pq.print();
	}
}