1+ class Node :
2+ def __init__ (self , value = None , nextNode = None , prevNode = None ):
3+ self .value = value
4+ self .nextNode = nextNode
5+ self .prevNode = prevNode
6+ 7+ def get_next_node (self ):
8+ return self .nextNode
9+ 10+ def get_prev_node (self ):
11+ return self .prevNode
12+ 13+ def get_node_val (self ):
14+ return self .value
15+ 16+ class CircularLinkedList :
17+ def __init__ (self ):
18+ self .head = None
19+ self .tail = None
20+ self .chain_len = 0
21+ 22+ def add_node_to_chain (self , value = None , Front = False ):
23+ new_node = Node (value = value )
24+ if Front :
25+ self .head .prevNode = new_node
26+ new_node .nextNode = self .head
27+ self .head = new_node
28+ # To make the linked_list circular, chain's head & tail should be connected
29+ self .head .prevNode = self .tail
30+ self .tail .nextNode = self .head
31+ else :
32+ if self .head is None :
33+ self .head = new_node
34+ self .tail = self .head
35+ else :
36+ self .tail .nextNode = new_node
37+ new_node .prevNode = self .tail
38+ self .tail = new_node
39+ self .tail .nextNode = self .head
40+ self .chain_len += 1
41+ 42+ def get_head_node (self ):
43+ return self .head
44+ 45+ def get_tail_node (self ):
46+ return self .tail
47+ 48+ def get_chain_length (self ):
49+ return self .chain_len
50+ 51+ def print_chain (self , circular = False ):
52+ head = self .head
53+ repeat = 0
54+ while head :
55+ print (' ' ,head .get_node_val (), "->" , end = '' )
56+ if head is self .get_tail_node ():
57+ if not repeat :
58+ repeat += 1
59+ else :
60+ print ("end_of_repetition" )
61+ break
62+ head = head .get_next_node ()
63+ else :
64+ print (' chain_end' )
65+ 66+ if __name__ == '__main__' :
67+ my_dl_list = CircularLinkedList ()
68+ 69+ my_dl_list .add_node_to_chain (1 )
70+ my_dl_list .add_node_to_chain (2 )
71+ my_dl_list .add_node_to_chain (3 )
72+ my_dl_list .add_node_to_chain (4 )
73+ 74+ print (f"Length of chain -> { my_dl_list .get_chain_length ()} )
75+ 76+ my_dl_list .print_chain ()
77+ 78+ print ('-- Now adding a node to the front of the chain --' )
79+ 80+ my_dl_list .add_node_to_chain (5 , Front = True )
81+ 82+ my_dl_list .print_chain ()
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