41 lines
667 B
Python
41 lines
667 B
Python
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def modpow(a, b, n):
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res = 1
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while b != 0:
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q, r = divmod(b, 2)
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if r == 1:
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res = (res * a) % n
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a = (a*a) % n
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b = q
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return res
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def euclid(a, b):
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table = []
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current = [a, b]
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while current[1] != 0:
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a, b = current
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q, r = divmod(a, b)
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current.append(q)
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table.append(current)
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current = [b, r]
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table[-1] += [0, 1]
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while True:
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_, _, _, x, y = table.pop()
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if not table:
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return current[0], x, y
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_, _, q = table[-1]
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table[-1] += [y, x - q * y]
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def modinv(a, n):
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_, x, _ = euclid(a, n)
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return x % n
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