数据结构之栈（java）

栈

先进后出FILO，在表的一端进行操作

1.顺序存储

2.链式存储

class Stack{
	//顺序栈
	private int top = -1; //栈顶 ，-1表示栈为空
	
	private int size; // 栈内的元素个数
	
	private int capacity = 10; //栈的容量

	private int[] array; //存放栈元素
	
	public Stack(int capacity) {
		super();
		this.capacity = capacity;
		array = new int[capacity];
	}

	public Stack() {
		super();
		array = new int[this.capacity];
	}
	
	/**
	 * 判断栈是否为空
	 * @return
	 */
	public boolean isEmpty() {
		return this.top == -1;
	}
	
	/**
	 * 入栈 push
	 * @return
	 */
	public void push(int data) {
		//判断栈是否满了
		if(array.length == size) {
			//扩容
			increCapacity();
		}
		array[++top] = data;
		size++;
	}
	
	/**
	 * 出栈
	 * 1.栈空，抛异常
	 * 2.栈不为空：size减一，移动栈顶指针
	 * @return
	 * @throws Exception 
	 */
	public int pop() throws Exception {
		if (this.isEmpty()) {
			throw new Exception("stack is empty !");
		}
		this.size--;
		return array[this.top--];//返回栈顶元素，移动栈顶指针
	}
	
	//获取栈顶元素
	public int getTopData() {
		if (isEmpty()) {
			return -1;
		}
		return array[this.top];
	}
	
	/**
	 * 扩容
	 */
	public void increCapacity() {
		this.capacity = this.size * 2 + 1; //默认
		int[] old_array = this.array;
		array = new int[this.capacity];
		System.arraycopy(old_array, 0, array, 0, size);
	}

	public int getTop() {
		return top;
	}

	public void setTop(int top) {
		this.top = top;
	}

	public int getSize() {
		return size;
	}

	public void setSize(int size) {
		this.size = size;
	}
	
}

class Node{
	
	Integer data;
	Node last;
	public Node(int data,Node last) {
		super();
		this.data = data;
		this.last = last;
	}
	public Node(int data) {
		super();
		this.data = data;
	}
	
	public Node() {
		super();
	}
	
	
	
}

class LinkStack{
	//链式栈
	 private Node top;
	 
	 private int size;
	 
	public LinkStack() {
		this.top = new Node();
	}
	
	/**
	 * 入栈
	 * 1. null 不允许入站
	 * 2. 判断是否为空栈
	 * @throws Exception 
	 */
	public void push(Integer data) throws Exception {
		if (data == null) {
			throw new Exception(" data can't be null");
		}else if (isEmpty() ) {
			Node node = new Node(data,null);
			this.top = node;
		}else {
			Node node = new Node(data,this.top);
			this.top = node;
		}
		size++;
	}
	
	/**
	 * 出zhan
	 * @throws Exception 
	 */
	public int pop() throws Exception {
		if (isEmpty()) {
			throw new Exception("stack is empty !");
		}
		int data = this.top.data;
		this.top = this.top.last;
		size--;
		return data;
	}
	
	public Integer getTopData() {
		if (isEmpty()) {
			return null;
		}
		return this.top.data;
	}
	
	/**
	 * 判断是否为空
	 * @return
	 */
	public boolean isEmpty() {
		return (this.top == null || this.top.data == null);
	}
	
	
	public Node getTop() {
		return top;
	}

	public void setTop(Node top) {
		this.top = top;
	}

	public int getSize() {
		return size;
	}

	public void setSize(int size) {
		this.size = size;
	}
	
}