power Algorithm
The multiplication of whole numbers may be thought as a repeated addition; that is, the multiplication of two numbers is equivalent to adding as many copy of one of them, the multiplicand, as the value of the other one, the multiplier. The multiplication of integers (including negative numbers), rational numbers (fractions) and real numbers is specify by a systematic generalization of this basic definition.
def actual_power(a: int, b: int):
"""
Function using divide and conquer to calculate a^b.
It only works for integer a,b.
"""
if b == 0:
return 1
if (b % 2) == 0:
return actual_power(a, int(b / 2)) * actual_power(a, int(b / 2))
else:
return a * actual_power(a, int(b / 2)) * actual_power(a, int(b / 2))
def power(a: int, b: int) -> float:
"""
>>> power(4,6)
4096
>>> power(2,3)
8
>>> power(-2,3)
-8
>>> power(2,-3)
0.125
>>> power(-2,-3)
-0.125
"""
if b < 0:
return 1 / actual_power(a, b)
return actual_power(a, b)
if __name__ == "__main__":
print(power(-2, -3))
