m2skills

simple LL python

Apr 18th, 2017
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Python 2.84 KB | None | 0 0
  1. # program to implement Linked List
  2.  
  3. class LinkedList:
  4.     def __init__(self):
  5.         self.head = None
  6.  
  7.     # returns true is LinkedList is Empty
  8.     def isEmpty(self):
  9.         if self.head is None:
  10.             return True
  11.         else:
  12.             return False
  13.  
  14.     # method adds elements to the left of the Linked List
  15.     def addToStart(self, data):
  16.         # create a temporary node
  17.         tempNode = Node(data)
  18.         tempNode.setLink(self.head)
  19.         self.head = tempNode
  20.         del tempNode
  21.  
  22.     # method adds elements to the right of the Linked List
  23.     def addToEnd(self, data):
  24.         start = self.head
  25.         tempNode = Node(data)
  26.         while start.getNextNode():
  27.             start = start.getNextNode()
  28.         start.setLink(tempNode)
  29.         del tempNode
  30.         return True
  31.  
  32.     # method displays Linked List
  33.     def display(self):
  34.         start = self.head
  35.         if start is None:
  36.             print("Empty List!!!")
  37.             return False
  38.  
  39.         while start:
  40.             print(str(start.getData()), end=" ")
  41.             start = start.link
  42.             if start:
  43.                 print("-->", end=" ")
  44.         print()
  45.  
  46.     # method removes item passed from the Linked List
  47.     def remove(self, item):
  48.         start = self.head
  49.         previous = None
  50.         found = False
  51.  
  52.         # search element in list
  53.         while not found:
  54.             if start.getData() == item:
  55.                 found = True
  56.             else:
  57.                 previous = start
  58.                 start = start.getNextNode()
  59.  
  60.         # if previous is None then the data is found at first position
  61.         if previous is None:
  62.             self.head = start.getNextNode()
  63.         else:
  64.             previous.setLink(start.getNextNode())
  65.         return found
  66.  
  67.  
  68.  
  69. # node class
  70. class Node:
  71.     # default value of data and link is none if no data is passed
  72.     def __init__(self, data=None, link=None):
  73.         self.data = data
  74.         self.link = link
  75.  
  76.     # method to update the data feild of Node
  77.     def updateData(self, data):
  78.         self.data = data
  79.  
  80.     # method to set Link feild the Node
  81.     def setLink(self, node):
  82.         self.link = node
  83.  
  84.     # method returns data feild of the Node
  85.     def getData(self):
  86.         return self.data
  87.  
  88.     # method returns address of the next Node
  89.     def getNextNode(self):
  90.         return self.link
  91.  
  92.  
  93. # main method
  94. # creating LinkedList
  95. myList = LinkedList()
  96.  
  97. # adding some elements to the start of LinkedList
  98. myList.addToStart(5)
  99. myList.addToStart(4)
  100. myList.addToStart(3)
  101. myList.addToStart(2)
  102. myList.addToStart(1)
  103.  
  104. myList.display()
  105.  
  106. # adding some elements to the End of the LinkedList
  107. myList.addToEnd(12)
  108. myList.addToEnd(13)
  109. myList.addToEnd(54)
  110. myList.display()
  111.  
  112. #removing some elements from the Linked List
  113. myList.remove(3)
  114. myList.remove(12)
  115. myList.display()
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