1+ # Node Class
2+ class _Node :
3+ __slots__ = '_element' , '_next'
4+ 5+ def __init__ (self , element , next ):
6+ self ._element = element
7+ self ._next = next
8+ 9+ # LinkedListQueue Class
10+ 11+ class LinkedListQueue :
12+ def __init__ (self ):
13+ self ._front = None
14+ self ._rear = None
15+ self ._size = 0
16+ 17+ def __len__ (self ):
18+ return self ._size
19+ 20+ def is_empty (self ):
21+ return self ._size == 0
22+ 23+ def enqueue (self , element ):
24+ newest = _Node (element , None )
25+ if self .is_empty ():
26+ self ._front = newest
27+ else :
28+ self ._rear ._next = newest
29+ self ._rear = newest
30+ self ._size += 1
31+ 32+ def dequeue (self ):
33+ if self .is_empty ():
34+ print ('Queue is Empty' )
35+ return
36+ e = self ._front ._element
37+ self ._front = self ._front ._next
38+ self ._size -= 1
39+ if self .is_empty ():
40+ self ._rear = None
41+ return e
42+ 43+ def peek (self ):
44+ if self .is_empty ():
45+ print ('Queue is Empty' )
46+ return
47+ return self ._front ._element
48+ 49+ def display (self ):
50+ p = self ._front
51+ while p :
52+ print (p ._element , end = ' <-- ' )
53+ p = p ._next
54+ print ()
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