divide and conquer and brute force algorithms for array-inversions counting

Author: maxwell-aladago

Diff for: divide_and_conquer/inversions.py

@@ -26,6 +26,17 @@ def count_inversions_bf(arr):
     -------
     num_inversions: The total number of inversions in `arr`
 
+    Examples
+    ---------
+
+     >>> count_inversions_bf([1, 4, 2, 4, 1])
+     3
+
+     >>> count_inversions_bf([1, 1, 2, 4, 4]
+     0
+
+     >>> count_inversions_bf([])
+     0
     """
 
     num_inversions = 0
@@ -53,6 +64,17 @@ def count_inversions_recursive(arr):
     C: a sorted copy of `arr`.
     num_inversions: int, the total number of inversions in 'arr'
 
+    Examples
+    --------
+
+    >>> count_inversions_recursive([1, 4, 2, 4, 1])
+    [1, 1, 2, 4, 4], 3
+
+    >>> count_inversions_recursive([1, 1, 2, 4, 4])
+    [1, 1, 2, 4, 4], 0
+
+    >>>> count_inversions_recursive([])
+    [], 0
     """
     if len(arr) <= 1:
         return arr, 0
@@ -87,6 +109,15 @@ def _count_cross_inversions(P, Q):
     R: array-like, a sorted array of the elements of `P` and `Q`
     num_inversion: int, the number of inversions across `P` and `Q`
 
+    Examples
+    --------
+
+    >>> _count_cross_inversions([1, 2, 3], [0, 2, 5])
+    [0, 1, 2, 2, 3, 5], 4
+
+    >>> _count_cross_inversions([1, 2, 3], [3, 4, 5])
+    [1, 2, 3, 3, 4, 5], 0
+
     """
 
     R = []