Added decimal_to_binary_recursion.py [Hacktoberfest]

conversions/decimal_to_binary_recursion.py

@@ -0,0 +1,65 @@
+def binary_recursive(decimal: int) -> str:
+    """
+    This takes in a positive integer value
+    and returns its binary equivalent.
+    >>> binary_recursive(1000)
+    '1111101000'
+    >>> binary_recursive("72")
+    Traceback (most recent call last):
+    ...
+    TypeError: unsupported operand type(s) for //: 'str' and 'int'
+    >>> binary_recursive("number")
+    Traceback (most recent call last):
+    ...
+    TypeError: unsupported operand type(s) for //: 'str' and 'int'
+    """
+    # Initialize exit base of the recursion function
+    if decimal == 1 or decimal == 0:
+        return str(decimal)
+    result = binary_recursive(decimal // 2) + str(decimal % 2)
+    return str(result)
+
+
+def main(number: str) -> str:
+    """
+    This function takes a parameter "number",
+    raises a ValueError for wrong inputs,
+    calls the function above and returns the output
+    with prefix "0b" & "-0b" for positive
+    and negative integers respectively.
+    >>> main(0)
+    '0b0'
+    >>> main(40)
+    '0b101000'
+    >>> main(-40)
+    '-0b101000'
+    >>> main(40.8)
+    Traceback (most recent call last):
+    ...
+    ValueError: Input value is not an integer
+    >>> main("forty")
+    Traceback (most recent call last):
+    ...
+    ValueError: Input value is not an integer
+    """
+    number = str(number).strip()
+    negative = False
+
+    if number.startswith("-"):
+        negative = True
+        number = number[1:]
+
+    if number.isnumeric():
+        if negative:
+            binary = "-0b" + binary_recursive(int(number))
+        else:
+            binary = "0b" + binary_recursive(int(number))
+        return binary
+    else:
+        raise ValueError("Input value is not an integer")
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()