chore(Python): added Recursive Insertion Sort (#457)

algorithms/Python/README.md

@@ -20,6 +20,7 @@
 
 1. [Factorial](recursion/factorial.py)
 2. [n-th Fibonacci number](recursion/n-th_fibonacci_number.py)
+3. [Recursive Insertion Sort](recursion/recursive_insertion_sort.py)
 
 ## Scheduling
 

algorithms/Python/recursion/recursive_insertion_sort.py

@@ -0,0 +1,30 @@
+"""
+Base Case: If array size is 1 or smaller, return.
+Recursively sort first n-1 elements.
+Insert last element at its correct position in sorted array.
+"""
+
+def insertionSort_rec(array, n):
+    # base case
+    if n <= 1:
+        return
+    # Sort first n-1 elements
+    insertionSort_rec(array, n-1)
+    '''Insert last element at its correct position
+        in sorted array.'''
+    end = array[n-1]
+    j = n-2
+    
+    # Move elements of arr[0..i-1], that are
+    # greater than key, to one position ahead
+    # of their current position
+    while (j >= 0 and array[j] > end):
+        array[j+1] = array[j]
+        j -= 1
+    array[j+1] = end
+
+
+arr = [6, 5, 2, 7, 12, 9, 1, 4]
+insertionSort_rec(arr, len(arr))
+print("Sorted array is:")
+print(arr)