CareerCup_3.2 - Stack tracking min value

StackWithMinValue.java

package Chapter3;

public class StackWithMinValue<T extends Comparable<T>> {
    private Node<T> top = null;

    public void push(T value) {
	//minimum value under new top node
	T min = top == null ? value : (top.min.compareTo(value) > 0 ? value
		: top.min);
	Node<T> next = top == null ? null : top;
	Node<T> newTop = new Node<T>(value, next, min);
	top = newTop;
    }

    public T pop() {
	if (top == null)
	    return null;
	Node<T> res = top;
	top = top.next;
	return res.value;
    }
    
    public T min() {
	if (top == null)
	    return null;
	return top.min;
    }
    
    public boolean isEmpty() {
	return top == null;
    }
    
    public static void main(String[] args) {
	StackWithMinValue<Integer> stack = new StackWithMinValue<>();
	for(int i = 0; i < 10; i++) {
	    stack.push(10 - i);
	}
	while(!stack.isEmpty()) {
	    System.out.println("current min elem is " + stack.min());
	    System.out.println("top elem is " + stack.pop());
	}
    }
}