From baf7a8da1b9adfe424138a3bbc4dbf358387d252 Mon Sep 17 00:00:00 2001
From: Sharan Krishnan <sharankrishnan6@gmail.com>
Date: Mon, 13 Jan 2020 19:02:24 +1100
Subject: [PATCH 1/2] A recursive insertion sort

---
 sorts/recursive_insertion_sort.py | 55 +++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 sorts/recursive_insertion_sort.py

diff --git a/sorts/recursive_insertion_sort.py b/sorts/recursive_insertion_sort.py
new file mode 100644
index 000000000000..1cd30c2e5738
--- /dev/null
+++ b/sorts/recursive_insertion_sort.py
@@ -0,0 +1,55 @@
+"""
+A recursive implementation of the insertion sort algorithm
+"""
+
+def rec_insertion_sort(collection, n):
+    """
+    Given a collection of numbers and its length, sorts the collections
+    in ascending order
+
+    :param collection: A mutable collection of heterogenous, comparable elements
+    :param n: The length of collections
+
+    >>> col = [1, 2, 1]
+    >>> rec_insertion_sort(col, len(col))
+    >>> print(col)
+    [1, 1, 2]
+
+    >>> col = [2, 1, 0, -1, -2]
+    >>> rec_insertion_sort(col, len(col))
+    >>> print(col)
+    [-2, -1, 0, 1, 2]
+
+    >>> col = [1]
+    >>> rec_insertion_sort(col, len(col))
+    >>> print(col)
+    [1]
+    """
+
+
+    #Checks if the entire collection has been sorted
+    if len(collection) <= 1 or n <= 1:
+        return
+
+
+    data_swap(collection, n-1)
+    rec_insertion_sort(collection, n-1)
+
+def data_swap(collection, index):
+
+    #Checks order between adjacent elements
+    if index >= len(collection) or collection[index - 1] <= collection[index]:
+        return
+
+    #Swaps adjacent elements since they are not in ascending order
+    collection[index - 1], collection[index] = (
+    collection[index], collection[index - 1]
+    )
+
+    data_swap(collection, index + 1)
+
+if __name__ == "__main__":
+    numbers = input("Enter integers seperated by spaces: ")
+    numbers = [int(num) for num in numbers.split()]
+    rec_insertion_sort(numbers, len(numbers))
+    print(numbers)

From 0af0c940e16581c6218ddc8eb45f38bbcffcbcb1 Mon Sep 17 00:00:00 2001
From: Sharan Krishnan <sharankrishnan6@gmail.com>
Date: Mon, 13 Jan 2020 20:27:17 +1100
Subject: [PATCH 2/2] added doctests and typehints

---
 sorts/recursive_insertion_sort.py | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/sorts/recursive_insertion_sort.py b/sorts/recursive_insertion_sort.py
index 1cd30c2e5738..a8bd2b9114ad 100644
--- a/sorts/recursive_insertion_sort.py
+++ b/sorts/recursive_insertion_sort.py
@@ -2,12 +2,14 @@
 A recursive implementation of the insertion sort algorithm
 """
 
-def rec_insertion_sort(collection, n):
+from typing import List
+
+def rec_insertion_sort(collection: List, n: int):
     """
     Given a collection of numbers and its length, sorts the collections
     in ascending order
 
-    :param collection: A mutable collection of heterogenous, comparable elements
+    :param collection: A mutable collection of comparable elements
     :param n: The length of collections
 
     >>> col = [1, 2, 1]
@@ -25,18 +27,33 @@ def rec_insertion_sort(collection, n):
     >>> print(col)
     [1]
     """
-
-
     #Checks if the entire collection has been sorted
     if len(collection) <= 1 or n <= 1:
         return
 
 
-    data_swap(collection, n-1)
+    insert_next(collection, n-1)
     rec_insertion_sort(collection, n-1)
 
-def data_swap(collection, index):
+def insert_next(collection: List, index: int):
+    """
+    Inserts the '(index-1)th' element into place
+
+    >>> col = [3, 2, 4, 2]
+    >>> insert_next(col, 1)
+    >>> print(col)
+    [2, 3, 4, 2]
+
+    >>> col = [3, 2, 3]
+    >>> insert_next(col, 2)
+    >>> print(col)
+    [3, 2, 3]
 
+    >>> col = []
+    >>> insert_next(col, 1)
+    >>> print(col)
+    []
+    """
     #Checks order between adjacent elements
     if index >= len(collection) or collection[index - 1] <= collection[index]:
         return
@@ -46,7 +63,7 @@ def data_swap(collection, index):
     collection[index], collection[index - 1]
     )
 
-    data_swap(collection, index + 1)
+    insert_next(collection, index + 1)
 
 if __name__ == "__main__":
     numbers = input("Enter integers seperated by spaces: ")