|
| 1 | +""" |
| 2 | +A Python implementation of the Reverse Selection Sort algorithm. |
| 3 | +
|
| 4 | +This algorithm progressively sorts the array by finding the largest |
| 5 | +element and reversing subarrays to place it at the correct position. |
| 6 | +
|
| 7 | +Inspired by the Pancake Sorting algorithm. |
| 8 | +For more information, see: https://en.wikipedia.org/wiki/Pancake_sorting |
| 9 | +
|
| 10 | +Examples: |
| 11 | +>>> reverse_selection_sort([45, 23, 11, 89, 54, 1, 3, 36]) |
| 12 | +[89, 54, 45, 36, 23, 11, 3, 1] |
| 13 | +>>> reverse_selection_sort([0, -89, 32, 5, 46, 8, 11]) |
| 14 | +[46, 32, 11, 8, 5, 0, -89] |
| 15 | +>>> reverse_selection_sort([34, -2, -1, 98, -42]) |
| 16 | +[98, 34, -1, -2, -42] |
| 17 | +""" |
| 18 | + |
| 19 | +def reverse_selection_sort(collection: list) -> list: |
| 20 | + """ |
| 21 | + A pure implementation of reverse selection sort algorithm in Python. |
| 22 | + :param collection: some mutable ordered collection with heterogeneous |
| 23 | + comparable items inside |
| 24 | + :return: the same collection sorted in descending order |
| 25 | + """ |
| 26 | + n = len(collection) |
| 27 | + for i in range(n): |
| 28 | + # Find the maximum element in the unsorted portion |
| 29 | + max_idx = i |
| 30 | + for j in range(i + 1, n): |
| 31 | + if collection[j] > collection[max_idx]: |
| 32 | + max_idx = j |
| 33 | + |
| 34 | + # Reverse the subarray from the current position to the end |
| 35 | + collection[i:max_idx+1] = reversed(collection[i:max_idx+1]) |
| 36 | + |
| 37 | + return collection |
| 38 | + |
| 39 | + |
| 40 | +if __name__ == "__main__": |
| 41 | + user_input = input("Enter numbers separated by a comma:\n").strip() |
| 42 | + unsorted = [int(item) for item in user_input.split(",")] |
| 43 | + print(reverse_selection_sort(unsorted)) |
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