class Stack:
def __init__(self):
self.items = UnorderedList()
def __str__(self):
return self.items.__str__()
def push(self, item):
self.items.append(item)
def pop(self):
return self.items.pop()
def peek(self):
current = self.items.head
for i in range(self.items.length() - 1):
current = current.getNext()
return current.getData()
def size(self):
return self.items.length()
class Queue:
def __init__(self):
self.items = UnorderedList()
def enqueue(self, item):
self.items.add(item)
def dequeue(self):
return self.items.pop()
def isEmpty(self):
return self.items.isEmpty()
def size(self):
return self.items.length()
class Deque:
def __init__(self):
self.items = UnorderedList()
def __str__(self):
return self.items.__str__()
def addFront(self, item):
self.items.add(item)
def addRear(self, item):
self.items.append(item)
def removeFront(self):
return self.items.popPos(0)
def removeRear(self):
return self.items.pop()
def isEmpty(self):
return self.items.isEmpty()
def size(self):
return self.items.length()