Consolidate decimal to binary iterative and recursive

DIRECTORY.md

@@ -145,7 +145,6 @@
   * [Binary To Octal](conversions/binary_to_octal.py)
   * [Decimal To Any](conversions/decimal_to_any.py)
   * [Decimal To Binary](conversions/decimal_to_binary.py)
-  * [Decimal To Binary Recursion](conversions/decimal_to_binary_recursion.py)
   * [Decimal To Hexadecimal](conversions/decimal_to_hexadecimal.py)
   * [Decimal To Octal](conversions/decimal_to_octal.py)
   * [Energy Conversions](conversions/energy_conversions.py)

conversions/decimal_to_binary.py

@@ -1,27 +1,27 @@
 """Convert a Decimal Number to a Binary Number."""
 
 
-def decimal_to_binary(num: int) -> str:
+def decimal_to_binary_iterative(num: int) -> str:
     """
     Convert an Integer Decimal Number to a Binary Number as str.
-    >>> decimal_to_binary(0)
+    >>> decimal_to_binary_iterative(0)
     '0b0'
-    >>> decimal_to_binary(2)
+    >>> decimal_to_binary_iterative(2)
     '0b10'
-    >>> decimal_to_binary(7)
+    >>> decimal_to_binary_iterative(7)
     '0b111'
-    >>> decimal_to_binary(35)
+    >>> decimal_to_binary_iterative(35)
     '0b100011'
     >>> # negatives work too
-    >>> decimal_to_binary(-2)
+    >>> decimal_to_binary_iterative(-2)
     '-0b10'
     >>> # other floats will error
-    >>> decimal_to_binary(16.16) # doctest: +ELLIPSIS
+    >>> decimal_to_binary_iterative(16.16) # doctest: +ELLIPSIS
     Traceback (most recent call last):
         ...
     TypeError: 'float' object cannot be interpreted as an integer
     >>> # strings will error as well
-    >>> decimal_to_binary('0xfffff') # doctest: +ELLIPSIS
+    >>> decimal_to_binary_iterative('0xfffff') # doctest: +ELLIPSIS
     Traceback (most recent call last):
         ...
     TypeError: 'str' object cannot be interpreted as an integer
@@ -52,7 +52,58 @@ def decimal_to_binary(num: int) -> str:
     return "0b" + "".join(str(e) for e in binary)
 
 
+def decimal_to_binary_recursive_helper(decimal: int) -> str:
+    """
+    Take a positive integer value and return its binary equivalent.
+    >>> decimal_to_binary_recursive_helper(1000)
+    '1111101000'
+    >>> decimal_to_binary_recursive_helper("72")
+    '1001000'
+    >>> decimal_to_binary_recursive_helper("number")
+    Traceback (most recent call last):
+        ...
+    ValueError: invalid literal for int() with base 10: 'number'
+    """
+    decimal = int(decimal)
+    if decimal in (0, 1):  # Exit cases for the recursion
+        return str(decimal)
+    div, mod = divmod(decimal, 2)
+    return decimal_to_binary_recursive_helper(div) + str(mod)
+
+
+def decimal_to_binary_recursive(number: str) -> str:
+    """
+    Take an integer value and raise ValueError for wrong inputs,
+    call the function above and return the output with prefix "0b" & "-0b"
+    for positive and negative integers respectively.
+    >>> decimal_to_binary_recursive(0)
+    '0b0'
+    >>> decimal_to_binary_recursive(40)
+    '0b101000'
+    >>> decimal_to_binary_recursive(-40)
+    '-0b101000'
+    >>> decimal_to_binary_recursive(40.8)
+    Traceback (most recent call last):
+        ...
+    ValueError: Input value is not an integer
+    >>> decimal_to_binary_recursive("forty")
+    Traceback (most recent call last):
+        ...
+    ValueError: Input value is not an integer
+    """
+    number = str(number).strip()
+    if not number:
+        raise ValueError("No input value was provided")
+    negative = "-" if number.startswith("-") else ""
+    number = number.lstrip("-")
+    if not number.isnumeric():
+        raise ValueError("Input value is not an integer")
+    return f"{negative}0b{decimal_to_binary_recursive_helper(int(number))}"
+
+
 if __name__ == "__main__":
     import doctest
 
     doctest.testmod()
+
+    print(decimal_to_binary_recursive(input("Input a decimal number: ")))