Implementing basic Data Structures in Python — Part 1| Daily Python #12

This article is a tutorial that covers the implementation of basic data structures — Linked List, Stack, and Queue. Later articles will cover the remaining data structures.

This article is a part of Daily Python challenge that I have taken up for myself. I will be writing short python articles daily.

There are no additional requirements for this article

Note: This article does not focus on explaining the concept of these basic data structures, the main purpose is to implement these data structures in Python 3.0

Let’s start with the Linked list

Inserting a node in the linked list

Deleting a node from the linked list

#Implementing basic data structures in Python - LinkedList
class Node:
  
  def __init__(self,value):
    self.value = value
    self.nextNode = None
class LinkedList:
  def __init__(self):
    self.headNode = None
    self.lastNode = None
  def insertNode(self,value):
    node = Node(value)
    if self.headNode == None:
      self.headNode = node
      self.lastNode = node
    else:
      self.lastNode.nextNode = node
      self.lastNode = node
    print(value,'inserted successfully')
  def insertNodeAfter(self,value,refValue):
    node = Node(value)
    if self.headNode == None:
      self.headNode = node
      self.lastNode = node
    else:
      iterator = self.headNode
      while iterator.value != refValue:
        iterator = iterator.nextNode
      node.nextNode = iterator.nextNode
      iterator.nextNode = node
    print(value,'inserted successfully')
  def traverseList(self):
    iterator = self.headNode
    while iterator != None:
      print(iterator.value)
      iterator = iterator.nextNode
  def deleteNode(self,value):
    iterator = self.headNode
    while iterator.nextNode.value != value:
      iterator = iterator.nextNode
    temp = iterator.nextNode
    iterator.nextNode = temp.nextNode
    del(temp)
    print(value,' deleted successfully')
ll = LinkedList()
ll.insertNode(1)
ll.insertNode(2)
ll.insertNode(3)
ll.traverseList()
ll.deleteNode(2)
ll.traverseList()
ll.insertNodeAfter(2,1)
ll.traverseList()

Snip of the output of the above code snippet.

The above LinkedList has 2 pointers: headNode and lastNode

For inserting a node at the end of the LinkedList, we simply create a node and then insert it as the ‘nextNode’ of the lastNode

Similarly, for inserting a node in between the LinkedList, we use an iterator to traverse the list and then insert the new node after the given node.

Now, we’ll proceed with the ‘Stack’

Last In First Out — Stack

#Implementing basic data structures in Python - Stack
class Stack:
  def __init__(self):
    self.top = -1
    self.data = []
  def push(self,value):
    print(value,' pushed successfully' )    
    self.data.append(value)
    self.top +=1 
  
  def pop(self):
    if self.top == -1:
        print('Stack is empty')        
        return 
    print(self.data[self.top],' popped successfully')
    del self.data[self.top]
    self.top -= 1
  def printStack(self):
    print('Stack : ',self.data)
stack = Stack()
stack.push(1)
stack.push(2)
stack.push(2)
stack.printStack()
stack.pop()
stack.printStack()

Snip of the Output of the above code snippet

Finally, we see the implementation of the Queue

First In First Out — Queue

class Queue:
    def __init__(self):
        self.front = -1
        self.end =  -1
        self.data = []
    
    def enqueue(self,value):
        print(value,' enqueued successfully')
        self.front = 0
        self.end += 1
        self.data.insert(self.front,value)
    
    def dequeue(self):
        if self.end == -1:
            print('Queue is empty')        
            return
        print(self.data[-1],' dequeued successfully')
        del self.data[self.end] 
        self.end -= 1
    def printQueue(self):
        print('Queue : ',self.data)
queue = Queue()
queue.enqueue(1)
queue.enqueue(2)
queue.enqueue(3)
queue.printQueue()
queue.dequeue()
queue.printQueue()

Snip of the Output of the above code snippet

I hope this article was helpful, do leave some claps if you liked it.

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