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Challenge 222: Equinox Shadows

curriculum/challenges/english/blocks/daily-coding-challenges-python/699c8e045ee7cb94ed2322dd.md

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--description--

Today is the equinox, when the sun is directly above the equator and perfectly overhead at noon. Given a time, determine the shadow cast by a 4-foot vertical pole.

  • The time will be a string in "HH:MM" 24-hour format (for example, "15:00" is 3pm).
  • You will only be given a time in 30 minute increments.

Rules:

  • The sun rises at 6am directly "east", and sets at 6pm directly "west".
  • A shadow always points opposite the sun.
  • The shadow's length (in feet) is the number of hours away from noon, cubed.
  • There is no shadow before sunrise (before 6am), after sunset (6pm or later), or at noon.

Return:

  • If a shadow exists, return "(length)ft (direction)". For example, "8ft west".
  • Otherwise, return "No shadow".

For example, given "10:00", return "8ft west" because 10am is 2 hours from noon, so 2<sup>3</sup> = 8 feet, and the shadow points west because the sun is in the east at 10am.

--hints--

get_shadow("10:00") should return "8ft west".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("10:00"), "8ft west")`)
}})

get_shadow("15:00") should return "27ft east".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("15:00"), "27ft east")`)
}})

get_shadow("12:00") should return "No shadow".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("12:00"), "No shadow")`)
}})

get_shadow("17:30") should return "166.375ft east".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("17:30"), "166.375ft east")`)
}})

get_shadow("05:00") should return "No shadow".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("05:00"), "No shadow")`)
}})

get_shadow("06:00") should return "216ft west".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("06:00"), "216ft west")`)
}})

get_shadow("18:00") should return "No shadow".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("18:00"), "No shadow")`)
}})

get_shadow("07:30") should return "91.125ft west".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("07:30"), "91.125ft west")`)
}})

get_shadow("00:00") should return "No shadow".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_shadow("00:00"), "No shadow")`)
}})

--seed--

--seed-contents--

py
def get_shadow(time):

    return time

--solutions--

py
def get_shadow(time):
    hour_str, minute_str = time.split(":")
    hours = int(hour_str)
    minutes = int(minute_str)
    time_in_hours = hours + minutes / 60

    if time_in_hours < 6 or time_in_hours >= 18 or time_in_hours == 12:
        return "No shadow"

    hours_from_noon = abs(12 - time_in_hours)
    length = hours_from_noon ** 3
    direction = "west" if time_in_hours < 12 else "east"

    return f"{length:g}ft {direction}"