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36 changes: 29 additions & 7 deletions stacks_queues/queue.py
Original file line number Diff line number Diff line change
Expand Up @@ -15,47 +15,69 @@ def __init__(self):
self.front = -1
self.rear = -1
self.size = 0


def enqueue(self, element):
""" Adds an element to the Queue
Raises a QueueFullException if all elements
In the store are occupied
returns None

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😎

"""
pass
if self.front == -1:
self.front = 0
self.rear = 0
if self.size == self.buffer_size:
raise QueueFullException('Queue is full')

self.store[self.rear] = element
self.rear = (self.rear + 1) % self.buffer_size
self.size += 1

def dequeue(self):
""" Removes and returns an element from the Queue
Raises a QueueEmptyException if
The Queue is empty.
"""
pass
if self.front == -1:

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Since you never check after dequeueing an element, whether the queue becomes empty and thus you should move the front and rear pointers back to -1, this conditional may not always work. Try using the empty method you implement below instead.

Suggested change
if self.front == -1:
if self.empty():

raise QueueEmptyException("The queue is empty")
element = self.store[self.front]
self.store[self.front] = None
self.size -= 1
self.front = (self.front + 1) % self.buffer_size

return element

def front(self):
""" Returns an element from the front
of the Queue and None if the Queue
is empty. Does not remove anything.
"""
pass

return self.store[self.front]

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def size(self):
""" Returns the number of elements in
The Queue
"""
pass
return self.size

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def empty(self):
""" Returns True if the Queue is empty
And False otherwise.
"""
pass
return (self.size == 0)

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def __str__(self):

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""" Returns the Queue in String form like:
[3, 4, 7]
Starting with the front of the Queue and
ending with the rear of the Queue.
"""
pass
list = []

for i in range(self.size):
list.append(self.store[(self.front + i) % self.buffer_size])

string = str(list)
return string

15 changes: 11 additions & 4 deletions stacks_queues/stack.py
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,8 @@ def push(self, element):
""" Adds an element to the top of the Stack.
Returns None
"""
pass

return self.store.add_first(element)

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Per the specification, the function should return None

Suggested change
return self.store.add_first(element)
self.store.add_first(element)


def pop(self):
""" Removes an element from the top
Expand All @@ -21,18 +22,24 @@ def pop(self):
The Stack is empty.
returns None
"""
pass
if self.store.head == None:
raise StackEmptyException("The stack is empty")

return self.store.remove_first()

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Per the specification, this should return None

Suggested change
return self.store.remove_first()
self.store.remove_first()


def empty(self):
""" Returns True if the Stack is empty
And False otherwise
"""
pass
if self.store.head == None:
return True
else:
return False
Comment on lines +34 to +37

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✨ This does work. You could also consider taking advantage of LinkedList's empty method


def __str__(self):

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""" Returns the Stack in String form like:
[3, 4, 7]
Starting with the top of the Stack and
ending with the bottom of the Stack.
"""
pass
return str(self.store)