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  1.  
  2. class Node(object):
  3.  
  4.     def __init__(self,d):
  5.         self.next_node = None
  6.         self.prev_node = None
  7.         self.data = d
  8.  
  9. class DoublyLinkedList(object):
  10.  
  11.     def __init__(self):
  12.         self.head = None
  13.         self.tail = None
  14.         self.size = 0
  15.  
  16.     def add(self,d):
  17.         new_node = Node(d)
  18.         if self.tail:
  19.             self.tail.next_node = new_node
  20.             new_node.next_node = None
  21.             new_node.prev_node = self.tail
  22.             self.tail=new_node
  23.         else:
  24.             self.head = new_node
  25.             self.tail = new_node
  26.             new_node.prev_node = None
  27.         self.size+=1
  28.  
  29.     def addBeg(self,d):
  30.         new_node = Node(d)
  31.         current_node = self.head
  32.         current_node.prev_node = new_node
  33.         new_node.prev_node = None
  34.         new_node.next_node = current_node
  35.         self.head = new_node
  36.         self.size+=1
  37.  
  38.     def add_at(self,d,index):
  39.         new_node = Node(d)
  40.         previous_node = None
  41.         current_node = self.head
  42.         i = 0
  43.         while i<index and current_node:
  44.             previous_node = current_node
  45.             current_node = current_node.next_node
  46.             i+=1
  47.         #once it reaches the desired index
  48.         if i==index:
  49.             previous_node.next_node = new_node
  50.             new_node.prev_node = previous_node
  51.             new_node.next_node = current_node
  52.             current_node.prev_node = new_node
  53.             self.size+=1
  54.             return True
  55.         else:
  56.             return False                #list ain't too long
  57.  
  58.  
  59.     def remove(self,d):
  60.         previous_node = None
  61.         current_node = self.head
  62.         while current_node:
  63.             if current_node.data == d:
  64.                 if previous_node:  #the node is somewhere in between
  65.                     #print(d)
  66.                     previous_node.next_node = current_node.next_node
  67.                     if current_node.next_node is None: #deleting last node
  68.                         current_node.prev_node=None
  69.                     else:
  70.                         current_node.next_node.prev_node = previous_node
  71.                 else:
  72.                     #it is the first node
  73.                     self.head = current_node.next_node
  74.                     current_node.next_node.prev_node = None
  75.                 self.size -= 1
  76.                 return True
  77.  
  78.             previous_node = current_node
  79.             current_node = current_node.next_node
  80.         return False
  81.  
  82.     def search(self,d):
  83.         current_node = self.head
  84.         while current_node:
  85.             if current_node.data == d:
  86.                 return True
  87.             current_node = current_node.next_node
  88.         return False
  89.  
  90.     #traverse through the linked list and store the elements in a list
  91.     def to_list(self):
  92.         lis = []
  93.         current_node = self.head
  94.         while current_node:
  95.             lis.append(current_node.data)
  96.             current_node = current_node.next_node
  97.         return lis
  98.  
  99. dll = DoublyLinkedList()
  100. dll.add(40)
  101. dll.add(50)
  102. dll.add(60)
  103. print(dll.to_list())
  104. dll.add(70)
  105. print(dll.to_list())
  106. dll.remove(50)
  107. print(dll.to_list())
  108. dll.remove(70)
  109. print(dll.to_list())
  110. dll.remove(40)
  111. print(dll.to_list())
  112.  
Success #stdin #stdout 0s 23304KB
comments (?)
stdin 


			

					
			
			

				
	
		
		
	
		
		 stdout
			
	

		
[40, 50, 60]
[40, 50, 60, 70]
[40, 60, 70]
[40, 60]
[60]


	

		
	 
	
	
			

					
			
			
			
			
			
			
			
			

			
			
			
		

	
		
		

			


			                        
			
			

				

	
					
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language:

						
Python (cpython 2.7.16)

					

					

						
created:
								
						
8 years ago

					

					

						
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