Python Program for Stooge Sort

Stooge Sort is a recursive sorting algorithm. It is not efficient for large datasets, but it helps beginners understand recursion and divide-and-conquer techniques. Given an array of numbers, sort it in ascending order using Stooge Sort.

Example:

Input: arr = [2, 4, 5, 3, 1]
Output: arr = [1 2 3 4 5]

How Stooge Sort Works

1. Compare the first and last elements of the array. If the first element is greater, swap them.
2. If the array has more than two elements:
   Recursively sort the first 2/3 of the array.
   Recursively sort the last 2/3 of the array.
   Recursively sort the first 2/3 again to confirm the middle elements are in place.

Python Implementation

def stoogesort(arr, l, h):
    if l >= h:
        return

    if arr[l] > arr[h]:
        arr[l], arr[h] = arr[h], arr[l]
    if h - l + 1 > 2:
        t = (h - l + 1) // 3

        stoogesort(arr, l, h - t)
        stoogesort(arr, l + t, h)
        stoogesort(arr, l, h - t)

arr = [2, 4, 5, 3, 1]
stoogesort(arr, 0, len(arr) - 1)
print("Sorted array:", arr)

Sorted array: [1, 2, 3, 4, 5]

Explanation:

• if arr[l] > arr[h]: arr[l], arr[h] = arr[h], arr[l]: Swaps first and last elements if they are in the wrong order.
• t = (h - l + 1) // 3: Calculates one-third of the current array length.
• stoogesort(arr, l, h - t): Recursively sorts the first two-thirds.
• stoogesort(arr, l + t, h): Recursively sorts the last two-thirds.
• stoogesort(arr, l, h - t): Sorts the first two-thirds again to ensure correct order of middle elements.

Please refer complete article on Stooge Sort for more details!