Add evil_number algorithm in maths/special_numbers

data_structures/linked_list/remove_nth_node_from_end_of_list.py

@@ -1,6 +1,5 @@
 """Learn more about this algorithm: https://www.geeksforgeeks.org/delete-nth-node-from-the-end-of-the-given-linked-list/"""
 
-
 from __future__ import annotations
 
 from dataclasses import dataclass

maths/special_numbers/evil_number.py

@@ -0,0 +1,67 @@
+"""
+== Evil Number ==
+An evil number is a non-negative integer that has an even number of 1s in its
+binary expansion. Numbers that are not evil are called odious numbers.
+
+Examples of evil numbers: 0, 3, 5, 6, 9, 10, 12, 15, 17, 18, 20, 23, 24, 27, ...
+Reference: https://en.wikipedia.org/wiki/Evil_number
+"""
+
+
+def is_evil_number(number: int) -> bool:
+    """
+    Check if a given number is an evil number.
+
+    A non-negative integer is evil if the sum of its binary digits (its Hamming weight)
+    is even.
+
+    :param number: A non-negative integer.
+    :return: True if number is an evil number, False otherwise.
+
+    >>> is_evil_number(0)
+    True
+    >>> is_evil_number(3)
+    True
+    >>> is_evil_number(5)
+    True
+    >>> is_evil_number(6)
+    True
+    >>> is_evil_number(9)
+    True
+    >>> is_evil_number(1)
+    False
+    >>> is_evil_number(2)
+    False
+    >>> is_evil_number(4)
+    False
+    >>> is_evil_number(7)
+    False
+    >>> is_evil_number(8)
+    False
+    >>> is_evil_number(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: Input must be a non-negative integer
+    >>> is_evil_number(5.5)
+    Traceback (most recent call last):
+        ...
+    TypeError: Input must be an integer
+    """
+    if not isinstance(number, int):
+        raise TypeError("Input must be an integer")
+    if number < 0:
+        raise ValueError("Input must be a non-negative integer")
+
+    count = 0
+    temp = number
+    while temp > 0:
+        if temp % 2 == 1:
+            count += 1
+        temp = temp // 2
+    return count % 2 == 0
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()