class Queue(object):
"""Creates a Queue class."""
def __init__(self):
"""Initialization of the queue."""
self._dll = DoublyLinkedList()
self._counter = self._dll._counter
self.head = self._dll.head
self.tail = self._dll.tail
def __len__(self):
"""Overwrite Python built in len function."""
return self._counter
def length(self):
"""Will use DLL counter for length."""
return self._dll._counter
def enqueue(self, data):
"""Add node to queue at head."""
self._dll.push(data)
def dequeue(self):
"""Remove node from queue at tail."""
return self._dll.shift()
def peek(self):
"""Display a value without removing it."""
if self.length == 0:
return None
return self._dll.tail.data
class Queue(object):
"""Class implementation of queue.
1. Enqueue: Add new head node.
2. Dequeue: Remove and return tail node value.
3. Peek: Display tail node,
4. Size: Display queue length.
"""
def __init__(self, iterable=None):
"""Instatiate Queue."""
self.dll = DoublyLinkedList(iterable)
def enqueue(self, contents):
"""Add new head node."""
self.dll.push(contents)
def dequeue(self):
"""Remove and return last node value."""
try:
old_tail_node_contents = self.dll.shift()
return old_tail_node_contents
except IndexError:
raise IndexError('Queue is already empty.')
def peek(self):
"""Display but don't remove the contents of tail node."""
try:
return self.dll.tail_node.contents
except AttributeError:
return None
def size(self):
"""Return Queue length."""
return self.dll.length
class Deque(object):
"""Deque implements a simple Python deque data structure."""
def __init__(self, iterable=None):
"""Init deque, iterate through data if provided as an argument."""
self.dll = DoublyLinkedList(iterable)
def append(self, data):
"""Append a node containing data to the head(end) of the deque."""
self.dll.push(data)
def appendleft(self, data):
"""Append a node containing data to the tail(front) of the deque."""
self.dll.append(data)
def pop(self):
"""Remove a value from the head(end) of the deque and return it.
Will raise an exception if the deque is empty."""
try:
return self.dll.pop()
except AttributeError:
raise IndexError("The deque is empty.")
def popleft(self):
"""Remove a value from the tail(front) of the deque and return it.
Will raise an exception if the deque is empty."""
try:
return self.dll.shift()
except AttributeError:
raise IndexError("The deque is empty.")
def peek(self):
"""Returns the value of the head(end) of the deque.
Returns None if the deque is empty."""
if self.dll.head is None:
return None
return self.dll.head.data
def peekleft(self):
"""Returns a value from the tail(front) of the deque.
Returns None if the deque is empty."""
if self.dll.tail is None:
return None
return self.dll.tail.data
def size(self):
"""Returns the count of nodes in the queue, 0 if empty."""
count = 0
current = self.dll.head
while current is not None:
count += 1
current = current._next
return count
class Deque(object):
"""Implementation of double-ended queue."""
def __init__(self, iterable=None):
"""Construct deque."""
self._dll = DoublyLinkedList(iterable)
def appendleft(self, val):
"""Add value at the from of deque."""
self._dll.push(val)
def append(self, val):
"""Add value to the back of deque."""
self._dll.append(val)
def pop(self):
"""Remove value from back of deque."""
try:
return self._dll.shift()
except IndexError:
raise IndexError('Cannot pop from an empty deque.')
def popleft(self):
"""Remove value from front of deque."""
try:
return self._dll.pop()
except IndexError:
raise IndexError('Cannot pop from an empty deque.')
def peek(self):
"""Return last value of deque."""
return self.tail.val if self.tail else None
def peekleft(self):
"""Return first value of deque."""
return self.head.val if self.head else None
def size(self):
"""Return size of deque."""
return self._dll._length
def __len__(self):
"""Return size of deque."""
return self.size()
@property
def head(self):
"""Return head."""
return self._dll.head
@property
def tail(self):
"""Return tail."""
return self._dll.tail
class Deque(object):
"""Using a doubly-linked list to build a deque."""
def __init__(self, iterable=None):
"""Initialize the deque."""
self.dll = DoublyLinkedList(iterable)
self.head_node = self.dll.head_node
self.tail_node = self.dll.tail_node
def append(self, contents):
"""Add node to this dll."""
self.dll.append(contents)
self.head_node = self.dll.head_node
self.tail_node = self.dll.tail_node
def append_left(self, contents):
"""Add a node to the left side of this dll."""
self.dll.push(contents)
self.head_node = self.dll.head_node
self.tail_node = self.dll.tail_node
def pop_left(self):
"""Pop a node from the left side of this dll."""
popped = self.dll.pop()
if popped is None:
raise ValueError
self.head_node = self.dll.head_node
return popped
def pop(self):
"""Pop a node from the right side of this dll."""
popped = self.dll.shift()
if popped is None:
raise ValueError
self.tail_node = self.dll.tail_node
return popped
def peek(self):
"""Look at the tail of the dll."""
if self.dll.length == 0:
return None
return self.dll.tail_node.contents
def peek_left(self):
"""Look at the head of the dll."""
if self.dll.length == 0:
return None
return self.dll.head_node.contents
def size(self):
"""Report the length of the queue."""
return self.dll.length
def breadth_first_traversal(self, starting_point):
"""Steps through the graph breadth-first.
Expects a starting point == value of a node in the graph."""
from dll import DoublyLinkedList
dll = DoublyLinkedList()
if self.has_node(starting_point) is False:
raise IndexError("That starting point is not in the graph.")
dll.push(starting_point)
result = []
while dll.size() > 0:
working_node = dll.shift()
if working_node not in result:
result.append(working_node)
for node in self.neighbors(working_node):
dll.push(node)
return result
def breadth_first(self, starting_point=None):
"""
This internal method is a generator that will output breadth first
traversal of a binary tree(left child, right child, parent),
one value at a time.
"""
if self.length == 0:
raise IndexError("You can't breadth-first traverse an empty Tree.")
from dll import DoublyLinkedList
unvisited = DoublyLinkedList()
if starting_point is None:
starting_point = self.root
elif self.contains(starting_point) is False:
raise IndexError('Starting point is not in the Tree.')
unvisited.push(starting_point)
visited = []
while unvisited.size() > 0:
current = unvisited.shift()
if current not in visited:
visited.append(current)
if current.left:
unvisited.push(current.left)
if current.right:
unvisited.push(current.right)
yield current.val