package com.duke.stack;

import java.util.Stack;

public class MinStack

{

private Stack<Integer> stack = null;

private int minElement = Integer.MAX_VALUE;

MinStack() {

stack = new Stack<Integer>();

}

// push the element

public void push(int data) {

if (stack.isEmpty()) {

stack.push(data);

minElement = data;

}

if (minElement < data) {

stack.push(data);

} else {

minElement = 2 * data - minElement;

stack.push(minElement);

}

}

// pop the element

public void pop()

{

if(stack.isEmpty())

{

System.out.println("Stack is empty");

return;

}

int popped = stack.pop();

if(popped < minElement)

{

minElement = 2*minElement - popped;

}

System.out.println("Removed: "+popped);

}

// get the minElement

public int getMin() {

System.out.println("Minimum element: "+minElement);

return minElement;

}

public static void main(String[] args) {

MinStack s = new MinStack();

s.push(3);

s.push(5);

s.getMin();//3

s.push(2);

s.push(1);

s.getMin();//1

s.pop();

s.getMin();//2

s.pop();

}

}