diff --git a/searches/interpolation_search.py b/searches/interpolation_search.py index 0591788aa40b..cb3e0011d0da 100644 --- a/searches/interpolation_search.py +++ b/searches/interpolation_search.py @@ -3,13 +3,41 @@ """ -def interpolation_search(sorted_collection, item): - """Pure implementation of interpolation search algorithm in Python - Be careful collection must be ascending sorted, otherwise result will be - unpredictable - :param sorted_collection: some ascending sorted collection with comparable items - :param item: item value to search - :return: index of found item or None if item is not found +def interpolation_search(sorted_collection: list[int], item: int) -> int | None: + """ + Searches for an item in a sorted collection by interpolation search algorithm. + + Args: + sorted_collection: sorted list of integers + item: item value to search + + Returns: + int: The index of the found item, or None if the item is not found. + Examples: + >>> interpolation_search([1, 2, 3, 4, 5], 2) + 1 + >>> interpolation_search([1, 2, 3, 4, 5], 4) + 3 + >>> interpolation_search([1, 2, 3, 4, 5], 6) is None + True + >>> interpolation_search([], 1) is None + True + >>> interpolation_search([100], 100) + 0 + >>> interpolation_search([1, 2, 3, 4, 5], 0) is None + True + >>> interpolation_search([1, 2, 3, 4, 5], 7) is None + True + >>> interpolation_search([1, 2, 3, 4, 5], 2) + 1 + >>> interpolation_search([1, 2, 3, 4, 5], 0) is None + True + >>> interpolation_search([1, 2, 3, 4, 5], 7) is None + True + >>> interpolation_search([1, 2, 3, 4, 5], 2) + 1 + >>> interpolation_search([5, 5, 5, 5, 5], 3) is None + True """ left = 0 right = len(sorted_collection) - 1 @@ -19,8 +47,7 @@ def interpolation_search(sorted_collection, item): if sorted_collection[left] == sorted_collection[right]: if sorted_collection[left] == item: return left - else: - return None + return None point = left + ((item - sorted_collection[left]) * (right - left)) // ( sorted_collection[right] - sorted_collection[left] @@ -33,7 +60,7 @@ def interpolation_search(sorted_collection, item): current_item = sorted_collection[point] if current_item == item: return point - elif point < left: + if point < left: right = left left = point elif point > right: @@ -46,22 +73,42 @@ def interpolation_search(sorted_collection, item): return None -def interpolation_search_by_recursion(sorted_collection, item, left, right): +def interpolation_search_by_recursion( + sorted_collection: list[int], item: int, left: int = 0, right: int | None = None +) -> int | None: """Pure implementation of interpolation search algorithm in Python by recursion Be careful collection must be ascending sorted, otherwise result will be unpredictable First recursion should be started with left=0 and right=(len(sorted_collection)-1) - :param sorted_collection: some ascending sorted collection with comparable items - :param item: item value to search - :return: index of found item or None if item is not found - """ + Args: + sorted_collection: some sorted collection with comparable items + item: item value to search + left: left index in collection + right: right index in collection + + Returns: + index of item in collection or None if item is not present + + Examples: + >>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 0) + 0 + >>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 15) + 4 + >>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 5) + 1 + >>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 100) is None + True + >>> interpolation_search_by_recursion([5, 5, 5, 5, 5], 3) is None + True + """ + if right is None: + right = len(sorted_collection) - 1 # avoid divided by 0 during interpolation if sorted_collection[left] == sorted_collection[right]: if sorted_collection[left] == item: return left - else: - return None + return None point = left + ((item - sorted_collection[left]) * (right - left)) // ( sorted_collection[right] - sorted_collection[left] @@ -73,64 +120,18 @@ def interpolation_search_by_recursion(sorted_collection, item, left, right): if sorted_collection[point] == item: return point - elif point < left: + if point < left: return interpolation_search_by_recursion(sorted_collection, item, point, left) - elif point > right: + if point > right: return interpolation_search_by_recursion(sorted_collection, item, right, left) - elif sorted_collection[point] > item: + if sorted_collection[point] > item: return interpolation_search_by_recursion( sorted_collection, item, left, point - 1 ) - else: - return interpolation_search_by_recursion( - sorted_collection, item, point + 1, right - ) - - -def __assert_sorted(collection): - """Check if collection is ascending sorted, if not - raises :py:class:`ValueError` - :param collection: collection - :return: True if collection is ascending sorted - :raise: :py:class:`ValueError` if collection is not ascending sorted - Examples: - >>> __assert_sorted([0, 1, 2, 4]) - True - >>> __assert_sorted([10, -1, 5]) - Traceback (most recent call last): - ... - ValueError: Collection must be ascending sorted - """ - if collection != sorted(collection): - raise ValueError("Collection must be ascending sorted") - return True + return interpolation_search_by_recursion(sorted_collection, item, point + 1, right) if __name__ == "__main__": - import sys + import doctest - """ - user_input = input('Enter numbers separated by comma:\n').strip() - collection = [int(item) for item in user_input.split(',')] - try: - __assert_sorted(collection) - except ValueError: - sys.exit('Sequence must be ascending sorted to apply interpolation search') - - target_input = input('Enter a single number to be found in the list:\n') - target = int(target_input) - """ - - debug = 0 - if debug == 1: - collection = [10, 30, 40, 45, 50, 66, 77, 93] - try: - __assert_sorted(collection) - except ValueError: - sys.exit("Sequence must be ascending sorted to apply interpolation search") - target = 67 - - result = interpolation_search(collection, target) - if result is not None: - print(f"{target} found at positions: {result}") - else: - print("Not found") + doctest.testmod()