diff --git a/README.md b/README.md index 3ea720683..e0dc15330 100644 --- a/README.md +++ b/README.md @@ -73,6 +73,17 @@ __Properties__ ###### View the algorithm in [action][selection-toptal] +## Shell sort +![alt text][shell-image] + +From [Wikipedia][shell-wiki]: Shellsort is a generalization of insertion sort that allows the exchange of items that are far apart. The idea is to arrange the list of elements so that, starting anywherem considereing every nth element gives a sorted list. Such a list is said to be h-sorted. Equivanelty, it can be thought of as h intterleaved lists, each individually sorted. + +__Properties__ +* Worst case performance O(nlog2 2n) +* Best case performance O(n log n) +* Average case performance depends on gap sequence + +###### View the algorithm in [action][shell-toptal] ## Search Algorithms @@ -123,6 +134,11 @@ Mathematically a bijective function is used on the characters' positions to encr [selection-toptal]: https://www.toptal.com/developers/sorting-algorithms/selection-sort [selection-wiki]: https://en.wikipedia.org/wiki/Selection_sort [selection-image]: https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/Selection_sort_animation.gif/250px-Selection_sort_animation.gif "Selection Sort Sort" + +[shell-toptal]: https://www.toptal.com/developers/sorting-algorithms/shell-sort +[shell-wiki]: https://en.wikipedia.org/wiki/Shellsort +[shell-image]: https://upload.wikimedia.org/wikipedia/commons/d/d8/Sorting_shellsort_anim.gif "Shell Sort" + [caesar]: https://upload.wikimedia.org/wikipedia/commons/4/4a/Caesar_cipher_left_shift_of_3.svg [linear-wiki]: https://en.wikipedia.org/wiki/Linear_search [linear-image]: http://www.tutorialspoint.com/data_structures_algorithms/images/linear_search.gif diff --git a/sorts/bogosort.py b/sorts/bogosort.py index 7e9d07f50..b8cb5b31b 100644 --- a/sorts/bogosort.py +++ b/sorts/bogosort.py @@ -1,5 +1,5 @@ """ -This is pure python implementation of bogosort algorithm +This is a pure python implementation of the bogosort algorithm For doctests run following command: python -m doctest -v bogosort.py or @@ -12,7 +12,7 @@ from __future__ import print_function import random def bogosort(collection): - """Pure implementation of bogosort algorithm in Python + """Pure implementation of the bogosort algorithm in Python :param collection: some mutable ordered collection with heterogeneous comparable items inside :return: the same collection ordered by ascending @@ -47,6 +47,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(bogosort(unsorted)) diff --git a/sorts/bubble_sort.py b/sorts/bubble_sort.py index 2baaff9ae..3bacb306f 100644 --- a/sorts/bubble_sort.py +++ b/sorts/bubble_sort.py @@ -47,6 +47,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(bubble_sort(unsorted)) diff --git a/sorts/heap_sort.py b/sorts/heap_sort.py index 5d1cbbbd0..ec262ad6b 100644 --- a/sorts/heap_sort.py +++ b/sorts/heap_sort.py @@ -1,4 +1,14 @@ +""" +This is a pure python implementation of the heap sort algorithm. +For doctests run following command: +python -m doctest -v heap_sort.py +or +python3 -m doctest -v heap_sort.py + +For manual testing run: +python insertion_sort.py +""" from __future__ import print_function @@ -17,13 +27,28 @@ def heapify(unsorted,index,heap_size): heapify(unsorted,largest,heap_size) def heap_sort(unsorted): - n=len(unsorted) - for i in range (n/2 - 1 , -1, -1) : - heapify(unsorted,i,n) - for i in range(n - 1, -1, -1): - unsorted[0], unsorted[i] = unsorted[i], unsorted[0] - heapify(unsorted,0,i) - return unsorted + """Pure implementation of the heap sort algorithm in Python + :param collection: some mutable ordered collection with heterogeneous + comparable items inside + :return: the same collection ordered by ascending + + Examples: + >>> heap_sort([0, 5, 3, 2, 2]) + [0, 2, 2, 3, 5] + + >>> heap_sort([]) + [] + + >>> heap_sort([-2, -5, -45]) + [-45, -5, -2] + """ + n=len(unsorted) + for i in range (n/2 - 1 , -1, -1): + heapify(unsorted,i,n) + for i in range(n - 1, -1, -1): + unsorted[0], unsorted[i] = unsorted[i], unsorted[0] + heapify(unsorted,0,i) + return unsorted if __name__ == '__main__': @@ -33,7 +58,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print (heap_sort(unsorted)) - diff --git a/sorts/insertion_sort.py b/sorts/insertion_sort.py index 501655e92..646ed68ca 100644 --- a/sorts/insertion_sort.py +++ b/sorts/insertion_sort.py @@ -1,5 +1,5 @@ """ -This is pure python implementation of insertion sort algorithm +This is a pure python implementation of the insertion sort algorithm For doctests run following command: python -m doctest -v insertion_sort.py @@ -13,7 +13,7 @@ from __future__ import print_function def insertion_sort(collection): - """Pure implementation of insertion sort algorithm in Python + """Pure implementation of the insertion sort algorithm in Python :param collection: some mutable ordered collection with heterogeneous comparable items inside @@ -51,6 +51,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(insertion_sort(unsorted)) diff --git a/sorts/merge_sort.py b/sorts/merge_sort.py index c34c395af..92a678016 100644 --- a/sorts/merge_sort.py +++ b/sorts/merge_sort.py @@ -1,5 +1,5 @@ """ -This is pure python implementation of merge sort algorithm +This is a pure python implementation of the merge sort algorithm For doctests run following command: python -m doctest -v merge_sort.py @@ -13,7 +13,7 @@ from __future__ import print_function def merge_sort(collection): - """Pure implementation of merge sort algorithm in Python + """Pure implementation of the merge sort algorithm in Python :param collection: some mutable ordered collection with heterogeneous comparable items inside @@ -71,6 +71,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(merge_sort(unsorted)) diff --git a/sorts/quick_sort.py b/sorts/quick_sort.py index 4e6516cd8..f8e61ede4 100644 --- a/sorts/quick_sort.py +++ b/sorts/quick_sort.py @@ -1,5 +1,5 @@ """ -This is pure python implementation of quick sort algorithm +This is a pure python implementation of the quick sort algorithm For doctests run following command: python -m doctest -v quick_sort.py @@ -62,6 +62,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(sort(unsorted)) diff --git a/sorts/selection_sort.py b/sorts/selection_sort.py index fbb94226d..80c306226 100644 --- a/sorts/selection_sort.py +++ b/sorts/selection_sort.py @@ -1,5 +1,5 @@ """ -This is pure python implementation of selection sort algorithm +This is a pure python implementation of the selection sort algorithm For doctests run following command: python -m doctest -v selection_sort.py @@ -13,7 +13,11 @@ from __future__ import print_function def selection_sort(collection): - """Pure implementation of selection sort algorithm in Python + """Pure implementation of the selection sort algorithm in Python + :param collection: some mutable ordered collection with heterogeneous + comparable items inside + :return: the same collection ordered by ascending + Examples: >>> selection_sort([0, 5, 3, 2, 2]) @@ -24,11 +28,8 @@ def selection_sort(collection): >>> selection_sort([-2, -5, -45]) [-45, -5, -2] - - :param collection: some mutable ordered collection with heterogeneous - comparable items inside - :return: the same collection ordered by ascending """ + length = len(collection) for i in range(length): least = i @@ -50,6 +51,6 @@ if __name__ == '__main__': else: input_function = input - user_input = input_function('Enter numbers separated by coma:\n') + user_input = input_function('Enter numbers separated by a comma:\n') unsorted = [int(item) for item in user_input.split(',')] print(selection_sort(unsorted)) diff --git a/sorts/shell_sort.py b/sorts/shell_sort.py new file mode 100644 index 000000000..4dc37240b --- /dev/null +++ b/sorts/shell_sort.py @@ -0,0 +1,58 @@ +""" +This is a pure python implementation of the shell sort algorithm + +For doctests run following command: +python -m doctest -v shell_sort.py +or +python3 -m doctest -v shell_sort.py + +For manual testing run: +python shell_sort.py +""" +from __future__ import print_function + + +def shell_sort(collection): + """Pure implementation of shell sort algorithm in Python + :param collection: Some mutable ordered collection with heterogeneous + comparable items inside + :return: the same collection ordered by ascending + + >>> shell_sort([0, 5, 3, 2, 2)] + [0, 2, 2, 3, 5] + + >>> shell_sort([]) + [] + + >>> shell_sort([-2, -5, -45]) + [-45, -5, -2] + """ + # Marcin Ciura's gap sequence + gaps = [701, 301, 132, 57, 23, 10, 4, 1] + + for gap in gaps: + i = gap + while i < len(collection): + temp = collection[i] + j = i + while j >= gap and collection[j-gap] > temp: + collection[j] = collection[j - gap] + j -= gap + collection[j] = temp + i += 1 + + + return collection + +if __name__ == '__main__': + import sys + # For python 2.x and 3.x compatibility: 3.x has not raw_input builtin + # otherwise 2.x's input builtin function is too "smart" + if sys.version_info.major < 3: + input_function = raw_input + else: + input_function = input + + user_input = input_function('Enter numbers separated by a comma:\n') + unsorted = [int(item) for item in user_input.split(',')] + print(shell_sort(unsorted))