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queue-implementation-using-fixed-sized-array.py
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72 lines (63 loc) · 1.66 KB
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#Implement queue using fixed array
#Source: https://github.com/careermonk/DataStructureAndAlgorithmicThinkingWithPython/blob/master/src/chapter05queues/QueueWithFixedSizeArray.py
class Queue(object):
def __init__(self, limit=5):
self.que = []
self.limit = limit
self.front = None
self.rear = None
self.size = 0
def isEmpty(self):
return self.size <= 0
def enQueue(self, item):
if self.size >= self.limit:
print('Queue Overflow!')
return
else:
self.que.append(item)
if self.front is None:
self.front = self.rear = 0
else:
self.rear = self.size
self.size += 1
print('Queue after enQueue', self.que)
def deQueue(self):
if self.size <= 0:
print('Queue Underflow!')
return 0
else:
self.que.pop(0)
self.size -= 1
if self.size == 0:
self.front = self.rear = None
else:
self.rear = self.size - 1
print('Queue after deQueue', self.que)
def queueRear(self):
if self.rear is None:
print("Sorry, the queue is empty!")
raise IndexError
return self.que[self.rear]
def queueFront(self):
if self.front is None:
print("Sorry, the queue is empty!")
raise IndexError
return self.que[self.front]
def size(self):
return self.size
que = Queue()
que.enQueue("first")
print ("Front: " + que.queueFront())
print ("Rear: " + que.queueRear())
que.enQueue("second")
print ("Front: " + que.queueFront())
print ("Rear: " + que.queueRear())
que.enQueue("third")
print ("Front: " + que.queueFront())
print ("Rear: " + que.queueRear())
que.deQueue()
print ("Front: " + que.queueFront())
print ("Rear: " + que.queueRear())
que.deQueue()
print ("Front: " + que.queueFront())
print ("Rear: " + que.queueRear())