freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/68e39ed6106dac2f0a98fd62.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
68e39ed6106dac2f0a98fd62	Challenge 80: Email Sorter	29	challenge-80

--description--

On October 29, 1971, the first email ever was sent, introducing the username@domain format we still use. Now, there are billions of email addresses.

In this challenge, you are given a list of email addresses and need to sort them alphabetically by domain name first (the part after the @), and username second (the part before the @).

• Sorting should be case-insensitive.
• If more than one email has the same domain, sort them by their username.
• Return an array of the sorted addresses.
• Returned addresses should retain their original case.

For example, given ["jill@mail.com", "john@example.com", "jane@example.com"], return ["jane@example.com", "john@example.com", "jill@mail.com"].

--hints--

sort(["jill@mail.com", "john@example.com", "jane@example.com"]) should return ["jane@example.com", "john@example.com", "jill@mail.com"].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(sort(["jill@mail.com", "john@example.com", "jane@example.com"]), ["jane@example.com", "john@example.com", "jill@mail.com"])`)
}})

sort(["bob@mail.com", "alice@zoo.com", "carol@mail.com"]) should return ["bob@mail.com", "carol@mail.com", "alice@zoo.com"].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(sort(["bob@mail.com", "alice@zoo.com", "carol@mail.com"]), ["bob@mail.com", "carol@mail.com", "alice@zoo.com"])`)
}})

sort(["user@z.com", "user@y.com", "user@x.com"]) should return ["user@x.com", "user@y.com", "user@z.com"].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(sort(["user@z.com", "user@y.com", "user@x.com"]), ["user@x.com", "user@y.com", "user@z.com"])`)
}})

sort(["sam@MAIL.com", "amy@mail.COM", "bob@Mail.com"]) should return ["amy@mail.COM", "bob@Mail.com", "sam@MAIL.com"].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(sort(["sam@MAIL.com", "amy@mail.COM", "bob@Mail.com"]), ["amy@mail.COM", "bob@Mail.com", "sam@MAIL.com"])`)
}})

sort(["simon@beta.com", "sammy@alpha.com", "Sarah@Alpha.com", "SAM@ALPHA.com", "Simone@Beta.com", "sara@alpha.com"]) should return ["SAM@ALPHA.com", "sammy@alpha.com", "sara@alpha.com", "Sarah@Alpha.com", "simon@beta.com", "Simone@Beta.com"].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(sort(["simon@beta.com", "sammy@alpha.com", "Sarah@Alpha.com", "SAM@ALPHA.com", "Simone@Beta.com", "sara@alpha.com"]), ["SAM@ALPHA.com", "sammy@alpha.com", "sara@alpha.com", "Sarah@Alpha.com", "simon@beta.com", "Simone@Beta.com"])`)
}})

--seed--

--seed-contents--

def sort(emails):

    return emails

--solutions--

def sort(emails):
    return sorted(
        emails,
        key=lambda email: (email.split('@')[1].lower(), email.split('@')[0].lower())
    )