Created
February 3, 2021 23:10
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Common divider and mod inverse
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def egcd(a, b): | |
if a == 0: | |
return (b, 0, 1) | |
else: | |
g, y, x = egcd(b % a, a) | |
return (g, x - (b // a) * y, y) | |
def modinv(a, m): | |
g, x, y = egcd(a, m) | |
if g != 1: | |
raise Exemption('modular inverse does not exist') | |
else: | |
return x % m |
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