diff --git a/sorts/intro_sort.py b/sorts/intro_sort.py new file mode 100644 index 000000000000..f0e3645adbb7 --- /dev/null +++ b/sorts/intro_sort.py @@ -0,0 +1,173 @@ +""" +Introspective Sort is hybrid sort (Quick Sort + Heap Sort + Insertion Sort) +if the size of the list is under 16, use insertion sort +https://en.wikipedia.org/wiki/Introsort +""" +import math + + +def insertion_sort(array: list, start: int = 0, end: int = 0) -> list: + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> insertion_sort(array, 0, len(array)) + [1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79] + """ + end = end or len(array) + for i in range(start, end): + temp_index = i + temp_index_value = array[i] + while temp_index != start and temp_index_value < array[temp_index - 1]: + array[temp_index] = array[temp_index - 1] + temp_index -= 1 + array[temp_index] = temp_index_value + return array + + +def heapify(array: list, index: int, heap_size: int) -> None: # Max Heap + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> heapify(array, len(array) // 2 ,len(array)) + """ + largest = index + left_index = 2 * index + 1 # Left Node + right_index = 2 * index + 2 # Right Node + + if left_index < heap_size and array[largest] < array[left_index]: + largest = left_index + + if right_index < heap_size and array[largest] < array[right_index]: + largest = right_index + + if largest != index: + array[index], array[largest] = array[largest], array[index] + heapify(array, largest, heap_size) + + +def heap_sort(array: list) -> list: + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> heap_sort(array) + [1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79] + """ + n = len(array) + + for i in range(n // 2, -1, -1): + heapify(array, i, n) + + for i in range(n - 1, 0, -1): + array[i], array[0] = array[0], array[i] + heapify(array, 0, i) + + return array + + +def median_of_3( + array: list, first_index: int, middle_index: int, last_index: int +) -> int: + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> median_of_3(array, 0, 0 + ((len(array) - 0) // 2) + 1, len(array) - 1) + 12 + """ + if (array[first_index] > array[middle_index]) != ( + array[first_index] > array[last_index] + ): + return array[first_index] + elif (array[middle_index] > array[first_index]) != ( + array[middle_index] > array[last_index] + ): + return array[middle_index] + else: + return array[last_index] + + +def partition(array: list, low: int, high: int, pivot: int) -> int: + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> partition(array, 0, len(array), 12) + 8 + """ + i = low + j = high + while True: + while array[i] < pivot: + i += 1 + j -= 1 + while pivot < array[j]: + j -= 1 + if i >= j: + return i + array[i], array[j] = array[j], array[i] + i += 1 + + +def sort(array: list) -> list: + """ + :param collection: some mutable ordered collection with heterogeneous + comparable items inside + :return: the same collection ordered by ascending + + Examples: + >>> sort([4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12]) + [1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79] + + >>> sort([-1, -5, -3, -13, -44]) + [-44, -13, -5, -3, -1] + + >>> sort([]) + [] + + >>> sort([5]) + [5] + + >>> sort([-3, 0, -7, 6, 23, -34]) + [-34, -7, -3, 0, 6, 23] + + >>> sort([1.7, 1.0, 3.3, 2.1, 0.3 ]) + [0.3, 1.0, 1.7, 2.1, 3.3] + + >>> sort(['d', 'a', 'b', 'e', 'c']) + ['a', 'b', 'c', 'd', 'e'] + """ + if len(array) == 0: + return array + max_depth = 2 * math.ceil(math.log2(len(array))) + size_threshold = 16 + return intro_sort(array, 0, len(array), size_threshold, max_depth) + + +def intro_sort( + array: list, start: int, end: int, size_threshold: int, max_depth: int +) -> list: + """ + >>> array = [4, 2, 6, 8, 1, 7, 8, 22, 14, 56, 27, 79, 23, 45, 14, 12] + + >>> max_depth = 2 * math.ceil(math.log2(len(array))) + + >>> intro_sort(array, 0, len(array), 16, max_depth) + [1, 2, 4, 6, 7, 8, 8, 12, 14, 14, 22, 23, 27, 45, 56, 79] + """ + while end - start > size_threshold: + if max_depth == 0: + return heap_sort(array) + max_depth -= 1 + pivot = median_of_3(array, start, start + ((end - start) // 2) + 1, end - 1) + p = partition(array, start, end, pivot) + intro_sort(array, p, end, size_threshold, max_depth) + end = p + return insertion_sort(array, start, end) + + +if __name__ == "__main__": + import doctest + + doctest.testmod() + + user_input = input("Enter numbers separated by a comma : ").strip() + unsorted = [float(item) for item in user_input.split(",")] + print(sort(unsorted))