//TO DO: include needed libraries
#include<iostream>
#include"stack.h"
using namespace std;

//---------------------------------------------------------------------------------------------------
//                                           initStack
//---------------------------------------------------------------------------------------------------
// Given a stack, initializes it to empty
void initStack(stack & s) {
	s.head = NULL;
	s.tail = NULL;
} // initStack()

  //---------------------------------------------------------------------------------------------------
  //                                           printStack
  //---------------------------------------------------------------------------------------------------
  // Given a stack: prints the keys of all nodes on the stack from top to bottom, left to right on 1 line
  // Ex: STACK: 22 87 39 45     (where 22 is the top and 45 is the bottom)
void printStack(stack & s) {
	node * w = s.head;
	cout << "STACK: ";
	if (w == NULL) {
		cout << "Empty";
	}
	else {
		while (w != NULL) {
			cout << w->key << " ";
			w = w->next;
		}
	}
	cout << "\n";
} // printStack()

  //---------------------------------------------------------------------------------------------------
  //                                           pop
  //---------------------------------------------------------------------------------------------------
  // removes the top element of the stack, deallocates it, and returns its key
int pop(stack & s) {
	if (s.head == NULL) {
		cout << "";
		return 0;
	}
	else {
		int n = s.head->key;
		s.head = s.head->next;
		return n;
	}
} // pop()

  //---------------------------------------------------------------------------------------------------
  //                                           push
  //---------------------------------------------------------------------------------------------------
  // Given a stack and the key of a new node; creates a new node and populates it with the given key;
  // pushes the new node on the stack.
void push(stack & s, int key) {
	node * m = new node;
	node * e = new node;
	m->key = key;
	m->next = NULL;

		m->next = s.head;
		s.head = m;

} // push()