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267b5eff40
* Added doctest and more explanation about Dijkstra execution. * tests were not passing with python2 due to missing __init__.py file at number_theory folder * Removed the dot at the beginning of the imported modules names because 'python3 -m doctest -v data_structures/hashing/*.py' and 'python3 -m doctest -v data_structures/stacks/*.py' were failing not finding hash_table.py and stack.py modules. * Moved global code to main scope and added doctest for project euler problems 1 to 14. * Added test case for negative input. * Changed N variable to do not use end of line scape because in case there is a space after it the script will break making it much more error prone. * Added problems description and doctests to the ones that were missing. Limited line length to 79 and executed python black over all scripts. * Changed the way files are loaded to support pytest call. * Added __init__.py to problems to make them modules and allow pytest execution. * Added project_euler folder to test units execution * Changed 'os.path.split(os.path.realpath(__file__))' to 'os.path.dirname()'
48 lines
1.1 KiB
Python
48 lines
1.1 KiB
Python
"""
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Problem:
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Each new term in the Fibonacci sequence is generated by adding the previous two
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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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from __future__ import print_function
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import math
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from decimal import *
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try:
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raw_input # Python 2
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except NameError:
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raw_input = input # Python 3
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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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getcontext().prec = 100
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phi = (Decimal(5) ** Decimal(0.5) + 1) / Decimal(2)
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index = (math.floor(math.log(n * (phi + 2), phi) - 1) // 3) * 3 + 2
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num = Decimal(round(phi ** Decimal(index + 1))) / (phi + 2)
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sum = num // 2
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return int(sum)
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if __name__ == "__main__":
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print(solution(int(raw_input().strip())))
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