1. DATA STRUCTURES IN PYTHON
By : Mrs Sangeeta M Chauhan , Gwalior
by Sangeeta M Chauhan
By: Sangeeta M Chauhan

2. Data Structure As the name shows It represents how data is stored/organized in Computer’s Memory .
Implementation of Data Structures can be done in two ways.
Simple Data Structures : Built from primitive data types (integers, real, charater, BooleanExample: Arrays or Linear List
Compound Data Structures: Simple Data structures are used to form more complex data structure. They are classified into two types
Linear: means elements are stored in sequential order
Example: Stack, Queue, Linked List
Non Linear : Data can be stored as multilevel Structure
Example Trees , Graphs
by Sangeeta M Chauhan

3. Introduction of Stack
Items stored in the order same as Stack Order (Last In First Out also called LIFO) means item stored one above another and when we want to remove any element from the Stack, as it is picked from the Top of the Stack i.e. the item that is added at last will remove first.
by Sangeeta M Chauhan

4. Have a look on different types of Stack in the real World
Stack of pebbles
Stack of Chapati/Roti
Stack of Coins
by Sangeeta M Chauhan

5. There are mainly Two types of Operations that can be done with Stack
push and 
pop.
Push: Insertion of an element on top of the stack is called Push
Pop: Removal an element from the top of the stack is called POP
Push and Pop Operations are done from single end called TOP
by Sangeeta M Chauhan

6. 24 56 4 9 2 Let’s understand it with an Example
Suppose we have a list of items which is to be inserted in the Stack of Size 5 24 56 4 9 2
by Sangeeta M Chauhan

7. Application of Stacks Expression Evaluation and Conversion
Stack is used to evaluate prefix, postfix and infix expressions. Stack can also be used to convert one form of expression to another. 
ii. Backtracking
Suppose we are finding a path for solving a particular problem and we have chosen a path and after following it later we realize that we have chosen wrong path. Now we need to go back to the beginning of the path to start with new path. This can be done with the help of stack. 
iii.Recursion When a Function call itself this process is called recursion. In each recursive call, there is need to save the current values of parameters, local variables and the return address (the address where the control has to return from the call).
Whenever a function calls to another function, first its arguments, then the return address and finally space for local variables is pushed onto the stack.
iv. To Reverse String
Stack is used to reverse a string. We push the characters of string one by one into stack and then pop character from stack. 
v. Function Call
Stack is also used to keep all information about the active functions or subroutines.  
by Sangeeta M Chauhan

8. Introduction of Queue
Items stored in the order same as Queue (Fast In First Out also called FIFO) means item stored one after another and the when we want to remove an item from the Queue the Item inserted first will remove first . As if waiting in a queue for the train tickets, the first one to stand in line is the first one to buy a ticket and get the reservation.
by Sangeeta M Chauhan

9. Queue is just like as queue in
Queue examples
Queue is just like as queue in
Cinema Hall
Railway Booking Counter
In Bank Counter etc.
by Sangeeta M Chauhan

10. Application of Queue
Queue, as the name suggests is used whenever we need to manage any group of tasks/objects in an First Come First Serve order for Example:
Serving multiple requests on a single shared resource, like a printer, CPU task scheduling etc.
Handling of interrupts in real-time systems. The interrupts are handled in the same order as they arrive i.e First come first served.
In real life scenario, Call Center phone systems uses Queues to hold the calls of people , in an order, until a service representative is free.
by Sangeeta M Chauhan

11. Insertion is done in the Queue from REAR end and Deletion Operations are done from FRONT end.
In Queue there are mainly two types of operations Insertion : Insertion of an element is done at REAR end, Insertion operation is also called ENQUEUE and Deletion: Deletion of an element is done at FRONT end, Deletion operation is also called DEQUEUE
by Sangeeta M Chauhan

12. Lets Understand through an Example.
Suppose we have a list of items which is to be inserted in the Queue of Size 5 24 56 4 9 2
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13. Some functions of list that are required to implement stacks/queues
Python List .append()
Add Single Element to The List
Python List .pop(index)
Removes Element at Given Index
Python List .pop()
Removes last element
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14. PRACTICAL IMPLEMENTATION OF STACK
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16. PRACTICAL IMPLEMENTATION OF QUEUE
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18. Stack using class
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19. QUEUE using class
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