Add Armstrong number check algorithm

maths/armstrong_number.py

@@ -0,0 +1,68 @@
+"""
+Armstrong Number (Narcissistic Number) Checker
+
+An Armstrong number is a number that is equal to the sum of its own digits
+each raised to the power of the number of digits.
+
+For example:
+- 153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153 (3 digits)
+- 9474 = 9^4 + 4^4 + 7^4 + 4^4 = 6561 + 256 + 2401 + 256 = 9474 (4 digits)
+
+Author: Rukaiya Khan
+"""
+
+
+def is_armstrong_number(number: int) -> bool:
+    """
+    Check if a number is an Armstrong number.
+
+    Args:
+        number: The number to check (must be non-negative)
+
+    Returns:
+        True if the number is an Armstrong number, False otherwise
+
+    Examples:
+        >>> is_armstrong_number(0)
+        True
+        >>> is_armstrong_number(1)
+        True
+        >>> is_armstrong_number(153)
+        True
+        >>> is_armstrong_number(370)
+        True
+        >>> is_armstrong_number(371)
+        True
+        >>> is_armstrong_number(407)
+        True
+        >>> is_armstrong_number(9474)
+        True
+        >>> is_armstrong_number(123)
+        False
+        >>> is_armstrong_number(100)
+        False
+    """
+    if number < 0:
+        return False
+
+    # Convert to string to easily get digits
+    num_str = str(number)
+    num_digits = len(num_str)
+
+    # Calculate sum of each digit raised to power of number of digits
+    sum_of_powers = sum(int(digit) ** num_digits for digit in num_str)
+
+    return sum_of_powers == number
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+
+    # Test with some examples
+    print("Armstrong numbers up to 1000:")
+    for num in range(1000):
+        if is_armstrong_number(num):
+            print(num, end=" ")
+    print()