iframe-proxy | Sunbelt Computer Software

32 lines (23 loc) · 675 Bytes

""" Multiply two numbers using Karatsuba algorithm """

def karatsuba(a, b):

"""

>>> karatsuba(15463, 23489) == 15463 * 23489

True

>>> karatsuba(3, 9) == 3 * 9

True

"""

if len(str(a)) == 1 or len(str(b)) == 1:

return a * b

else:

m1 = max(len(str(a)), len(str(b)))

m2 = m1 // 2

a1, a2 = divmod(a, 10 ** m2)

b1, b2 = divmod(b, 10 ** m2)

x = karatsuba(a2, b2)

y = karatsuba((a1 + a2), (b1 + b2))

z = karatsuba(a1, b1)

return (z * 10 ** (2 * m2)) + ((y - z - x) * 10 ** (m2)) + (x)

def main():

print(karatsuba(15463, 23489))

if __name__ == "__main__":

main()

Sunbelt Computer Software