/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package mystack;

/**
 *
 * @author kvaradar
 */
public class MyStack implements Stack {
    
  //  homepage.cs.uiowa.edu/~kvaradar/fall2013/ds.html
    
    Object [] myArray;
    int top;
    public static final int CAPACITY = 1000;
    
    public MyStack() { 
        myArray = new Object[CAPACITY];
        top = -1;
    }

    public int size() { // O(1)
        return (top + 1);
    }
    
    public boolean isEmpty() { // O(1)
        return (size() == 0);
    }
    
    public void push(Object a) { // Let n be size.
        // normal push: O(1)
        // resizing push: O(n)
        
        if (size() == myArray.length) {
            Object [] tempArray = new Object [2 * myArray.length];
            for (int i = 0; i < myArray.length; i++)
                tempArray[i] = myArray[i];
            myArray = tempArray;
        }
        
        myArray[top + 1] = a;
        top = top + 1;
    }
    
    public Object top() { // O(1)
        //exceptional case: method called when stack empty
        
        return myArray[top];
    }
    
    public Object pop() { // O(1)
        //exceptional case
        
        Object temp = myArray[top];
        top--;
        myArray[ top + 1] = null; //facilitate garbage collection
        return temp;
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        
        
    }
    
    public static void reverse(Object [] arr, Stack sta) {
        for (int i = 0; i < arr.length; i++)
            sta.push(arr[i]);
        
        for (int i = 0; i < arr.length; i++)
            arr[i] = sta.pop();
    }
}