🚀 Day 55/150 – Insertion Sort in Python

Insertion Sort builds the sorted list one element at a time.

It takes each element and inserts it into its correct position among the already sorted elements.

 Works like sorting playing cards in your hand.

🔹 Method 1 – Basic Insertion Sort

numbers = [12, 11, 13, 5, 6] for i in range(1, len(numbers)): key = numbers[i] j = i - 1 while j >= 0 and numbers[j] > key: numbers[j + 1] = numbers[j] j -= 1 numbers[j + 1] = key print("Sorted List:", numbers)

🔹 Method 2 – Taking User Input

numbers = list(map(int, input("Enter numbers: ").split())) for i in range(1, len(numbers)): key = numbers[i] j = i - 1 while j >= 0 and numbers[j] > key: numbers[j + 1] = numbers[j] j -= 1 numbers[j + 1] = key print("Sorted List:", numbers)

🔹 Method 3 – Sorting in Descending Order

numbers = [12, 11, 13, 5, 6] for i in range(1, len(numbers)): key = numbers[i] j = i - 1 while j >= 0 and numbers[j] < key: numbers[j + 1] = numbers[j] j -= 1 numbers[j + 1] = key print("Descending Order:", numbers)

🔹 Method 4 – Using Function

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 return arr print(insertion_sort([12, 11, 13, 5, 6]))

💡 Key Takeaways

• Builds the sorted list one element at a time
• Efficient for small or nearly sorted lists
• Time Complexity: O(n²) in the worst case
• Stable sorting algorithm (keeps equal elements in order)