Created
August 13, 2015 00:46
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python FIFO queue
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class Node(object): | |
def __init__(self, value): | |
self.value = value | |
self.next = None | |
def __repr__(self): | |
return 'Node %s' % self.value | |
class Queue(object): | |
"""A FIFO queue.""" | |
def __init__(self): | |
self.length = 0 | |
self.head = None | |
self.last = None | |
def __repr__(self): | |
result = '' | |
node = self.head | |
while node: | |
result += ' %s' % node | |
node = node.next | |
return result | |
def is_empty(self): | |
return self.length == 0 | |
def add(self, value): | |
new_node = Node(value) | |
if self.length == 0: | |
self.head = new_node | |
self.last = new_node | |
else: | |
self.last.next = new_node | |
self.last = new_node | |
self.length += 1 | |
def remove(self): | |
if not self.head: | |
return | |
value = self.head.value | |
self.head = self.head.next | |
self.length -= 1 | |
return value | |
q = Queue() | |
q.add(2) | |
q.add(3) | |
q.add(4) | |
q.add(5) | |
print q | |
# Node 2 Node 3 Node 4 Node 5 | |
print q.is_empty() | |
# False | |
q.remove() | |
print q | |
# Node 3 Node 4 Node 5 |
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