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29 lines
661 B
Python
29 lines
661 B
Python
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def bin_exp_mod(a, n, b):
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"""
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>>> bin_exp_mod(3, 4, 5)
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1
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>>> bin_exp_mod(7, 13, 10)
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7
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"""
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# mod b
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assert not (b == 0), "This cannot accept modulo that is == 0"
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if n == 0:
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return 1
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if n % 2 == 1:
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return (bin_exp_mod(a, n - 1, b) * a) % b
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r = bin_exp_mod(a, n / 2, b)
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return (r * r) % b
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if __name__ == "__main__":
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try:
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BASE = int(input("Enter Base : ").strip())
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POWER = int(input("Enter Power : ").strip())
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MODULO = int(input("Enter Modulo : ").strip())
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except ValueError:
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print("Invalid literal for integer")
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print(bin_exp_mod(BASE, POWER, MODULO))
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