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42 lines
846 B
Python
42 lines
846 B
Python
"""
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Problem:
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Each new term in the Fibonacci sequence is generated by adding the previous
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two terms. By starting with 1 and 2, the first 10 terms will be:
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1,2,3,5,8,13,21,34,55,89,..
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By considering the terms in the Fibonacci sequence whose values do not exceed
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n, find the sum of the even-valued terms. e.g. for n=10, we have {2,8}, sum is
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10.
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"""
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def solution(n):
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"""Returns the sum of all fibonacci sequence even elements that are lower
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or equals to n.
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>>> solution(10)
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10
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>>> solution(15)
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10
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>>> solution(2)
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2
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>>> solution(1)
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0
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>>> solution(34)
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44
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"""
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if n <= 1:
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return 0
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a = 0
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b = 2
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count = 0
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while 4 * b + a <= n:
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a, b = b, 4 * b + a
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count += a
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return count + b
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if __name__ == "__main__":
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print(solution(int(input().strip())))
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