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c510a7da7b
* Added doomsday algorithm * Adding unit-tests to doomsday algorithm * running black on doomsday * adding doctest and fixing a black issue [doomsday] * Update doomsday.py * fixing black issue [doomsday] * Update other/doomsday.py * Update doomsday.py * adding more doctests (following review comment) [doomsday] Co-authored-by: John Law <johnlaw.po@gmail.com>
60 lines
1.5 KiB
Python
60 lines
1.5 KiB
Python
#!/bin/python3
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# Doomsday algorithm info: https://en.wikipedia.org/wiki/Doomsday_rule
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DOOMSDAY_LEAP = [4, 1, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5]
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DOOMSDAY_NOT_LEAP = [3, 7, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5]
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WEEK_DAY_NAMES = {
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0: "Sunday",
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1: "Monday",
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2: "Tuesday",
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3: "Wednesday",
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4: "Thursday",
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5: "Friday",
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6: "Saturday",
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}
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def get_week_day(year: int, month: int, day: int) -> str:
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"""Returns the week-day name out of a given date.
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>>> get_week_day(2020, 10, 24)
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'Saturday'
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>>> get_week_day(2017, 10, 24)
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'Tuesday'
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>>> get_week_day(2019, 5, 3)
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'Friday'
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>>> get_week_day(1970, 9, 16)
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'Wednesday'
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>>> get_week_day(1870, 8, 13)
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'Saturday'
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>>> get_week_day(2040, 3, 14)
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'Wednesday'
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"""
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# minimal input check:
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assert len(str(year)) > 2, "year should be in YYYY format"
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assert 1 <= month <= 12, "month should be between 1 to 12"
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assert 1 <= day <= 31, "day should be between 1 to 31"
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# Doomsday algorithm:
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century = year // 100
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century_anchor = (5 * (century % 4) + 2) % 7
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centurian = year % 100
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centurian_m = centurian % 12
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dooms_day = (
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(centurian // 12) + centurian_m + (centurian_m // 4) + century_anchor
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) % 7
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day_anchor = (
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DOOMSDAY_NOT_LEAP[month - 1]
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if (year % 4 != 0) or (centurian == 0 and (year % 400) == 0)
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else DOOMSDAY_LEAP[month - 1]
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)
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week_day = (dooms_day + day - day_anchor) % 7
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return WEEK_DAY_NAMES[week_day]
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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