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16 lines
695 B
Python
16 lines
695 B
Python
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def collatz_sequence(n):
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"""Collatz conjecture: start with any positive integer n.Next termis obtained from the previous term as follows:
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if the previous term is even, the next term is one half the previous term.
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If the previous term is odd, the next term is 3 times the previous term plus 1.
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The conjecture states the sequence will always reach 1 regaardess of starting n."""
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sequence = [n]
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while n != 1:
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if n % 2 == 0:# even
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n //= 2
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else:
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n = 3*n +1
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sequence.append(n)
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return sequence
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answer = max([(len(collatz_sequence(i)), i) for i in range(1,1000000)])
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print("Longest Collatz sequence under one million is %d with length %d" % (answer[1],answer[0]))
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