#!/usr/bin/env python
# coding: utf-8

# # Implementation of Deque
# 
# In this lecture we will implement our own Deque class!
# 
# ## Methods and Attributes
# 
# * Deque() creates a new deque that is empty. It needs no parameters and returns an empty deque.
# * addFront(item) adds a new item to the front of the deque. It needs the item and returns nothing.
# * addRear(item) adds a new item to the rear of the deque. It needs the item and returns nothing.
# * removeFront() removes the front item from the deque. It needs no parameters and returns the item. The deque is modified.
# * removeRear() removes the rear item from the deque. It needs no parameters and returns the item. The deque is modified.
# * isEmpty() tests to see whether the deque is empty. It needs no parameters and returns a boolean value.
# * size() returns the number of items in the deque. It needs no parameters and returns an integer.
# 
# ## Deque Implementation

# In[1]:


class Deque:
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return self.items == []

    def addFront(self, item):
        self.items.append(item)

    def addRear(self, item):
        self.items.insert(0,item)

    def removeFront(self):
        return self.items.pop()

    def removeRear(self):
        return self.items.pop(0)

    def size(self):
        return len(self.items)


# In[10]:


d = Deque()


# In[11]:


d.addFront('hello')


# In[12]:


d.addRear('world')


# In[13]:


d.size()


# In[14]:


print d.removeFront() + ' ' +  d.removeRear()


# In[15]:


d.size()


# ## Good Job!