class Queue(object):
def __init__(self):
self.front = None
self.back = None
self.count = 0
def enqueue(self, x):
if self.count == 0:
self.front = LinkedListNode(x)
self.back = self.front
else:
temp = LinkedListNode(x)
self.back.setNext(temp)
self.back = temp
self.count += 1
def dequeue(self):
if self.count == 0:
return None
else:
temp = self.front.getData()
self.front = self.front.getNext()
if self.count == 1:
self.back = None
self.count -= 1
return temp
def peek(self):
if self.front == None:
return None
else:
return self.front.data
def __len__(self):
return self.count
def enqueue(self, x):
if self.count == 0:
self.front = LinkedListNode(x)
self.back = self.front
else:
temp = LinkedListNode(x)
self.back.setNext(temp)
self.back = temp
self.count += 1
def enqueue(self, x):
"""Puts the given object into the queue, at the back."""
if self.count == 0:
self.front = LinkedListNode(x)
self.back = self.front
else:
temp = LinkedListNode(x)
self.back.setNext(temp)
self.back = temp
self.count += 1
def enqueue(self, x): """Puts the given object into the queue, at the back.""" if self.count == 0: self.front = LinkedListNode(x) self.back = self.front else: temp = LinkedListNode(x) self.back.setNext(temp) self.back = temp self.count += 1
class Queue(object):
"""A queue, similar to the one in our Miller and Ranum textbook."""
def __init__(self):
"""Initializes an empty queue."""
self.front = None
self.back = None
self.count = 0
def enqueue(self, x):
"""Puts the given object into the queue, at the back."""
if self.count == 0:
self.front = LinkedListNode(x)
self.back = self.front
else:
temp = LinkedListNode(x)
self.back.setNext(temp)
self.back = temp
self.count += 1
def dequeue(self):
"""If the queue is not empty, then removes the front object and returns it. If the queue is empty, then does nothing and returns None."""
if self.count == 0:
return None
else:
temp = self.front.getData()
self.front = self.front.getNext()
if self.count == 1:
self.back = None
self.count -= 1
return temp
def peek(self):
"""If the queue is not empty, then returns the front object, without removing it from the queue. If the queue is empty, then returns None."""
if self.front == None:
return None
else:
return self.front.getData()
def __len__(self):
"""Returns the number of objects in the queue."""
return self.count
def __str__(self):
"""Returns a human-readable string representation of the queue, from front to back, assuming that the objects in the queue themselves respond to the __str__ method."""
if self.count == 0:
return "()"
elif self.count == 1:
return "(" + str(self.front.getData()) + ")"
else:
# There are at least two objects; commas are needed.
string = "(" + str(self.front.getData())
current = self.front.getNext()
while current != None:
string += ", " + str(current.getData())
current = current.getNext()
string += ")"
return string
class Queue(object):
"""A queue, similar to the one in our Miller and Ranum textbook."""
def __init__(self):
"""Initializes an empty queue."""
self.front = None
self.back = None
self.count = 0
def enqueue(self, x):
"""Puts the given object into the queue, at the back."""
if self.count == 0:
self.front = LinkedListNode(x)
self.back = self.front
else:
temp = LinkedListNode(x)
self.back.setNext(temp)
self.back = temp
self.count += 1
def dequeue(self):
"""If the queue is not empty, then removes the front object and returns it. If the queue is empty, then does nothing and returns None."""
if self.count == 0:
return None
else:
temp = self.front.getData()
self.front = self.front.getNext()
if self.count == 1:
self.back = None
self.count -= 1
return temp
def peek(self):
"""If the queue is not empty, then returns the front object, without removing it from the queue. If the queue is empty, then returns None."""
if self.front == None:
return None
else:
return self.front.getData()
def __len__(self):
"""Returns the number of objects in the queue."""
return self.count
def __str__(self):
"""Returns a human-readable string representation of the queue, from front to back, assuming that the objects in the queue themselves respond to the __str__ method."""
if self.count == 0:
return "()"
elif self.count == 1:
return "(" + str(self.front.getData()) + ")"
else:
# There are at least two objects; commas are needed.
string = "(" + str(self.front.getData())
current = self.front.getNext()
while current != None:
string += ", " + str(current.getData())
current = current.getNext()
string += ")"
return string
def append(self, data):
new_node = LinkedListNode(data)
if self.head == None:
self.head = new_node
return
