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63 lines
1.6 KiB
Python
63 lines
1.6 KiB
Python
"""
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Greatest Common Divisor.
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Wikipedia reference: https://en.wikipedia.org/wiki/Greatest_common_divisor
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"""
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def greatest_common_divisor(a, b):
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"""
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Calculate Greatest Common Divisor (GCD).
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>>> greatest_common_divisor(24, 40)
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8
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>>> greatest_common_divisor(1, 1)
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1
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>>> greatest_common_divisor(1, 800)
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1
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>>> greatest_common_divisor(11, 37)
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1
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>>> greatest_common_divisor(3, 5)
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1
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>>> greatest_common_divisor(16, 4)
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4
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"""
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return b if a == 0 else greatest_common_divisor(b % a, a)
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"""
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Below method is more memory efficient because it does not use the stack (chunk of
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memory). While above method is good, uses more memory for huge numbers because of the
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recursive calls required to calculate the greatest common divisor.
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"""
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def gcd_by_iterative(x, y):
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"""
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>>> gcd_by_iterative(24, 40)
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8
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>>> greatest_common_divisor(24, 40) == gcd_by_iterative(24, 40)
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True
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"""
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while y: # --> when y=0 then loop will terminate and return x as final GCD.
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x, y = y, x % y
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return x
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def main():
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"""Call Greatest Common Divisor function."""
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try:
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nums = input("Enter two integers separated by comma (,): ").split(",")
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num_1 = int(nums[0])
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num_2 = int(nums[1])
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print(
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f"greatest_common_divisor({num_1}, {num_2}) = "
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f"{greatest_common_divisor(num_1, num_2)}"
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)
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print(f"By iterative gcd({num_1}, {num_2}) = {gcd_by_iterative(num_1, num_2)}")
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except (IndexError, UnboundLocalError, ValueError):
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print("Wrong input")
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if __name__ == "__main__":
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main()
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