07 5. Data Structures

5. Data Structures

5.1 Linked Lists

• A linked list is a collection of nodes, where each node contains data and a pointer to the next node.
  

Node Class:

class Node:
    def __init__(self, data):

self.data = data

self.next = None

Example Traversal:

head = Node(1)

second = Node(2)

head.next = second

current = head

while current is not None:
    print(current.data)

current = current.next

5.2 Stacks (Last-In-First-Out)

• Operations:
  
  • push: Add item to the top
    
  • pop: Remove item from the top
    
  • peek: View the top item without removing
    
  • isEmpty: Check if stack is empty
    

Example (using list):

stack = []

stack.append(10)

stack.append(20)

print(stack.pop())  # 20

5.3 Queues (First-In-First-Out)

• Operations:
  
  • enqueue: Add to the rear
    
  • dequeue: Remove from the front
    

Example (using list):

from collections import deque

queue = deque()

queue.append(1) # enqueue

queue.append(2)

print(queue.popleft())  # dequeue: 1

5.6 Stack and Queue Implementations

• Stack and Queue can be implemented using both arrays and linked structures.
  
• Arrays offer fast indexing but fixed size.
  
• Linked structures use dynamic memory and are flexible in size.
  

This concludes the detailed beginner-friendly computing notes for topics 1 to 5. Let me know if you’d like practice questions, concept maps, or a printable version!