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37 changes: 30 additions & 7 deletions stacks_queues/queue.py
Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@

INITIAL_QUEUE_SIZE = 20

class QueueFullException(Exception):
Expand All @@ -23,39 +22,63 @@ def enqueue(self, element):
In the store are occupied
returns None
"""

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pass

if self.size == self.buffer_size:
raise QueueFullException()

if self.front == -1:
self.front = self.rear = 0

# if self.rear == self.buffer_size:
# self.rear = 0

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


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

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pass
if self.size == 0:
raise QueueEmptyException()

self.size -= 1
element = self.store[self.front]
self.front += 1
if self.front == self.buffer_size:
self.front = 0
return element

def front(self):

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""" Returns an element from the front
of the Queue and None if the Queue
is empty. Does not remove anything.
"""
pass
if self.size == 0:
return None
else:
return self.store[self.front]


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

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def empty(self):

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

def __str__(self):
""" 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
return str(self.store[self.front:self.rear])

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This will only work in the case that the rear pointer has an index greater than that of the front index.

In the case that the rear pointer has wrapped around to the front of the queue, the rear pointer will be less than the front pointer and your code will end up returning an empty string.

11 changes: 7 additions & 4 deletions stacks_queues/stack.py
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ 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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def pop(self):
""" Removes an element from the top
Expand All @@ -21,18 +21,21 @@ def pop(self):
The Stack is empty.
returns None
"""
pass
if self.store.empty():
raise StackEmptyException()
else:
return self.store.remove_first()

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def empty(self):
""" Returns True if the Stack is empty
And False otherwise
"""
pass
return self.store.empty()

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def __str__(self):
""" 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)

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