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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()'
46 lines
1.1 KiB
Python
46 lines
1.1 KiB
Python
# -*- coding: utf-8 -*-
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"""
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Problem:
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The sum of the squares of the first ten natural numbers is,
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1^2 + 2^2 + ... + 10^2 = 385
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The square of the sum of the first ten natural numbers is,
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(1 + 2 + ... + 10)^2 = 552 = 3025
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Hence the difference between the sum of the squares of the first ten natural
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numbers and the square of the sum is 3025 − 385 = 2640.
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Find the difference between the sum of the squares of the first N natural
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numbers and the square of the sum.
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"""
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from __future__ import print_function
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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 difference between the sum of the squares of the first n
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natural numbers and the square of the sum.
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>>> solution(10)
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2640
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>>> solution(15)
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13160
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>>> solution(20)
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41230
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>>> solution(50)
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1582700
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"""
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suma = n * (n + 1) / 2
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suma **= 2
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sumb = n * (n + 1) * (2 * n + 1) / 6
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return int(suma - sumb)
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if __name__ == "__main__":
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print(solution(int(raw_input().strip())))
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