cc150_3_2.java

package cc150_3_2;

public class MinStack<T extends Comparable<T>> {
	private Node<T> top = null;
	private Node<T> min_top = null;
	
	public void push(T value){
		
		T minvalue =  top == null ? value :(min_top.item.compareTo(value) > 0 ? value : min_top.item); 
		
		Node<T> temp = top == null ? new Node<T>(value): top;
		Node<T> min_temp = min_top == null ? new Node<T>(value):min_top;
		
		Node<T> next = new Node<T>(value);
		Node<T> min_next = new Node<T>(minvalue);
		next.next = temp;
		min_next = min_temp;
		top = next;
		min_top = min_temp;
	}
	
	public T pop(){
		if (top == null)
		    return null;
		Node<T> current = top;
		top = top.next;
		min_top = min_top;
		
		return current.item;
	}
	
	public T min(){
		if (top == null)
		    return null;
		Node<T> current = min_top;
			
		return current.item;
	}
	
    public boolean isEmpty() {
    	return top == null;
    }
	
    public static void main(String[] args){
    	
    	MinStack test = new MinStack();
    	
    	for (int i = 5;i < 15; i++){
    		test.push(i);
    	}
    	while(!test.isEmpty()) {
    		System.out.println("Current min is " + test.min());
    		System.out.println("Current top element is " + test.pop());
    	}
    }
    
	
}

Node.java

public class Node<Item> {
	Item item = null;
	Node next = null;
	public Node(Item item){
		this.item = item;
		this.next = null;
	}

}