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Hajipur, Bihar, 844101
Python
Introduction to Python
Python Basics
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Python Syntax
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Python Comments
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Python Variables
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Python Data Types
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Python Casting
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Python I/O
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Python Operators
Cotrol Structures
Data Structures
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Python Strings
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Python Lists
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Python Tuples
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Python Dictionaries
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Python Sets
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Python Arrays
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Python Bytes and Bytearray
Date and Time
Functions and Module
File Handling
Python OOP
Advanced Concepts
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Python Scope
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Python Modules
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Python JSON
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Python RegEx
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Python PIP
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Python Try...Except
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Python String Formatting
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Python User Input
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Python VirtualEnv
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Python Math
Python DSA
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Python DSA
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Lists and Arrays
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Python Stacks
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Python Queues
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Linked Lists
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Python Hash Tables
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Python Trees
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Python Binary Trees
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Binary Search Trees
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Python AVL Trees
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Python Graphs
Searching Algorithms
Sorting Algorithms
Python Insertion Sort
Insertion Sort builds the final sorted list one element at a time. It is simple, intuitive, and works well with small or nearly sorted lists.
It’s the same way we often sort playing cards in our hands!
🔹 How Insertion Sort Works
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Start from the second element
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Compare it with elements before
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Shift larger elements one position to the right
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Insert the current element into its correct position
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Repeat for all elements
🔹 Insertion Sort in Python
def insertion_sort(arr):
for i in range(1, len(arr)):
key = arr[i]
j = i - 1
while j >= 0 and arr[j] > key:
arr[j + 1] = arr[j]
j -= 1
arr[j + 1] = key
Example
numbers = [12, 11, 13, 5, 6]
insertion_sort(numbers)
print("Sorted array:", numbers)
✅ Output:
Sorted array: [5, 6, 11, 12, 13]
🔹 Visual Example (First 2 Steps)
Start: [12, 11, 13, 5, 6]
→ Compare 11 with 12 → [11, 12, 13, 5, 6]
→ Compare 13 with 12 → No change
🔹 Time Complexity
| Case | Time |
|---|---|
| Best Case | O(n) |
| Average | O(n²) |
| Worst Case | O(n²) |
| Space | O(1) |
It performs better than bubble/selection sort for nearly sorted lists.
🔹 Use Cases of Insertion Sort
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Best for small datasets
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When input is already partially sorted
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Stable sort (preserves order of equal elements)
Practice Questions
Q1. Write a Python program to sort the list [7, 3, 5, 2] using insertion sort.
Q2. Write a Python program to modify insertion sort to sort a list in descending order.
Q3. Write a Python program to accept a list of numbers from the user and sort them using insertion sort.
Q4. Write a Python program to count and print how many times the array is modified during insertion sort.
Q5. Write a Python program to sort a list of strings alphabetically using insertion sort.
Q6. Write a Python program to print the list after each insertion step during insertion sort.
Q7. Write a Python program to sort only the first half of a list using insertion sort.
Q8. Write a Python program to implement insertion sort without using a separate function (write code directly in the main block).
Q9. Write a Python program to sort a list using reverse logic in insertion sort (from end to start).
Q10. Write a Python program to compare the time taken by insertion sort and selection sort to sort a list of 1,000 random numbers.
Python
Introduction to Python
Python Basics
-
Python Syntax
-
Python Comments
-
Python Variables
-
Python Data Types
-
Python Casting
-
Python I/O
-
Python Operators
Cotrol Structures
Data Structures
-
Python Strings
-
Python Lists
-
Python Tuples
-
Python Dictionaries
-
Python Sets
-
Python Arrays
-
Python Bytes and Bytearray
Date and Time
Functions and Module
File Handling
Python OOP
Advanced Concepts
-
Python Scope
-
Python Modules
-
Python JSON
-
Python RegEx
-
Python PIP
-
Python Try...Except
-
Python String Formatting
-
Python User Input
-
Python VirtualEnv
-
Python Math
Python DSA
-
Python DSA
-
Lists and Arrays
-
Python Stacks
-
Python Queues
-
Linked Lists
-
Python Hash Tables
-
Python Trees
-
Python Binary Trees
-
Binary Search Trees
-
Python AVL Trees
-
Python Graphs
Searching Algorithms
Sorting Algorithms
