def inverseOf(a:int, n:int):
"""
find the inverse of a in the ring of Z base n
(in mod n)
a:int = number which inverse is in question
n:int = mod (ring of Z) base
"""
if pulv.gcd(n,a).value != 1 :
raise ValueError("the number is not relatively prime to the mod base!")
else:
result = pulv.gcd(n,a).t
while result <= 0:
# keep adding base n until the inverse result is positive
result += n
return result
def test_longer_remainder_gcd_reversed_params(self):
"""
test the scenario of product of primes gcd but the parameters are on reversed order
"""
result = pulverizer.gcd(91, 221)
# assert
self.assertEqual([result.value, result.s, result.t], [13, 5, -2],
"reversed order incorrect")
def test_longer_remainder_gcd(self):
"""
the scenario is for the gcd of two numbers which directly product of two primes.
"""
result = pulverizer.gcd(221, 91)
# assert
self.assertEqual([result.value, result.s, result.t], [13, -2, 5],
"longer gcd linear comb incorrect")
def test_divisior_as_first_param_gcd(self):
"""
the scenario is for the divisor as first param
"""
# set
result = pulverizer.gcd(50, 400)
# assert
self.assertEqual([result.value, result.s, result.t], [50, 1, 0],
"the result list order is incorrect")
def test_divisor_as_gcd(self):
"""
the scenario is if the divisor is the gcd in the second parameter.
"""
# setup
result = pulverizer.gcd(400, 20)
# assert
self.assertEqual(result.value, 20, "value is not match the gcd")
self.assertEqual([result.s, result.t], [0, 1],
"the s and t coefficients is not correct")