Python/maths/binary_exponentiation.py

"""Binary Exponentiation."""

# Author : Junth Basnet
# Time Complexity : O(logn)


def binary_exponentiation(a, n):

    if (n == 0):
        return 1

    elif (n % 2 == 1):
        return binary_exponentiation(a, n - 1) * a

    else:
        b = binary_exponentiation(a, n / 2)
        return b * b


if __name__ == "__main__":
    try:
        BASE = int(input("Enter Base : ").strip())
        POWER = int(input("Enter Power : ").strip())
    except ValueError:
        print("Invalid literal for integer")

    RESULT = binary_exponentiation(BASE, POWER)
    print("{}^({}) : {}".format(BASE, POWER, RESULT))