Add merge insertion sort

sorts/merge_insertion_sort.py

@@ -0,0 +1,103 @@
+"""
+This is a pure Python implementation of the quick sort algorithm
+
+For doctests run following command:
+python -m doctest -v merge_insertion_sort.py
+or
+python3 -m doctest -v merge_insertion_sort.py
+
+For manual testing run:
+python merge_insertion_sort.py
+"""
+
+
+def merge_insertion_sort(collection):
+    """Pure implementation of merge-insertion sort algorithm in Python
+
+    :param collection: some mutable ordered collection with heterogeneous
+    comparable items inside
+    :return: the same collection ordered by ascending
+
+    Examples:
+    >>> merge_insertion_sort([0, 5, 3, 2, 2])
+    [0, 2, 2, 3, 5]
+
+    >>> merge_insertion_sort([])
+    []
+
+    >>> merge_insertion_sort([-2, -5, -45])
+    [-45, -5, -2]
+    """
+
+    def binary_search_insertion(sorted_list, item):
+        left = 0
+        right = len(sorted_list) - 1
+        while left <= right:
+            middle = (left + right) // 2
+            if left == right:
+                if sorted_list[middle] < item:
+                    left = middle + 1
+                    break
+                else:
+                    break
+            elif sorted_list[middle] < item:
+                left = middle + 1
+            else:
+                right = middle - 1
+        sorted_list.insert(left, item)
+        return sorted_list
+
+    def sortlist_2d(list_2d):
+        def merge(left, right):
+            result = []
+            while left and right:
+                if left[0][0] < right[0][0]:
+                    result.append(left.pop(0))
+                else:
+                    result.append(right.pop(0))
+            return result + left + right
+
+        length = len(list_2d)
+        if length <= 1:
+            return list_2d
+        middle = length // 2
+        return merge(sortlist_2d(list_2d[:middle]), sortlist_2d(list_2d[middle:]))
+
+    if len(collection) <= 1:
+        return collection
+
+    two_paired_list = []
+    is_surplus = False
+    for i in range(0, len(collection), 2):
+        if i == len(collection) - 1:
+            is_surplus = True
+        else:
+            if collection[i] < collection[i + 1]:
+                two_paired_list.append([collection[i], collection[i + 1]])
+            else:
+                two_paired_list.append([collection[i + 1], collection[i]])
+    sorted_list_2d = sortlist_2d(two_paired_list)
+    result = [i[0] for i in sorted_list_2d]
+    result.append(sorted_list_2d[-1][1])
+
+    if is_surplus:
+        pivot = collection[-1]
+        result = binary_search_insertion(result, pivot)
+
+    is_surplus_inserted_before_this_index = False
+    for i in range(len(sorted_list_2d) - 1):
+        if result[i] == collection[-i]:
+            is_surplus_inserted_before_this_index = True
+        pivot = sorted_list_2d[i][1]
+        if is_surplus_inserted_before_this_index:
+            result = result[: i + 2] + binary_search_insertion(result[i + 2 :], pivot)
+        else:
+            result = result[: i + 1] + binary_search_insertion(result[i + 1 :], pivot)
+
+    return result
+
+
+if __name__ == "__main__":
+    user_input = input("Enter numbers separated by a comma:\n").strip()
+    unsorted = [int(item) for item in user_input.split(",")]
+    print(merge_insertion_sort(unsorted))