power_using_recursion.py

"""
== Raise base to the power of exponent using recursion ==
 Input -->
 Enter the base: 3
 Enter the exponent: 4
 Output -->
 3 to the power of 4 is 81
 Input -->
 Enter the base: 2
 Enter the exponent: 0
 Output -->
 2 to the power of 0 is 1
"""


def power(base: int, exponent: int) -> float:
 """
 Calculate the power of a base raised to an exponent.

 >>> power(3, 4)
 81
 >>> power(2, 0)
 1
 >>> all(power(base, exponent) == pow(base, exponent)
 ... for base in range(-10, 10) for exponent in range(10))
 True
 >>> power('a', 1)
 'a'
 >>> power('a', 2)
 Traceback (most recent call last):
 ...
 TypeError: can't multiply sequence by non-int of type 'str'
 >>> power('a', 'b')
 Traceback (most recent call last):
 ...
 TypeError: unsupported operand type(s) for -: 'str' and 'int'
 >>> power(2, -1)
 Traceback (most recent call last):
 ...
 RecursionError: maximum recursion depth exceeded
 >>> power(0, 0)
 1
 >>> power(0, 1)
 0
 >>> power(5,6)
 15625
 >>> power(23, 12)
 21914624432020321
 """
 return base * power(base, (exponent - 1)) if exponent else 1


if __name__ == "__main__":
 from doctest import testmod

 testmod()
 print("Raise base to the power of exponent using recursion...")
 base = int(input("Enter the base: ").strip())
 exponent = int(input("Enter the exponent: ").strip())
 result = power(base, abs(exponent))
 if exponent < 0: # power() does not properly deal w/ negative exponents
 result = 1 / result
 print(f"{base} to the power of {exponent} is {result}")