package stack;

import list.Node;

/**

* Created by admin on 2017/9/20.

*/

/*

顺序栈

数组实现栈，栈顶元素top为

*/

public class SeqStack {

private int DEFAULT_SIZE = 16;//栈的初始默认长度

private int capacity;//栈的自定义长度

private int size; //栈中元素个数

private Node[] nodes; //用数组存储节点

public SeqStack() {

capacity = DEFAULT_SIZE;

nodes = new Node[capacity];

}

public SeqStack(int capacity) {

this.capacity = capacity;

nodes = new Node[capacity];

}

/**

* 入栈

* @param item

*/

public void push(Node item){

if(size+1 > capacity) {

System.out.println("栈满了");

return;

}

nodes[size++] = item;

}

/**

* 出栈

* @return

*/

public Node pop(){

if(isEmpty())

{

System.out.println("队空，不能出栈");

return null;

}

Node oldnode = nodes[size - 1];

nodes[--size] = null;

return oldnode;

}

/**

* 返回展大哥你元素

* @return

*/

public Node peek(){

if(isEmpty())

{

System.out.println("队空");

return null;

}

return nodes[size-1];

}

public int lenght(){

return size;

}

public boolean isEmpty(){

return size ==0;

}

public void clear(){

for(int i =0; i< size; i++){

nodes[i] = null;

}

size = 0;

}

}