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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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