Validating Email Addresses With a Filter

You are given an integer N followed by N email addresses. Your task is to print a list containing only valid email addresses in lexicographical order.

Valid email addresses must follow these rules:

• It must have the username@websitename.extension format type.
• The username can only contain letters, digits, dashes and underscores [a – z], [A – Z], [0 – 9], [ _ – ].
• The website name can only have letters and digits [a – z], [A – Z], [0 – 9].
• The extension can only contain letters [a – z], [A – Z].
• The maximum length of the extension is 3.
  

Concept

A filter takes a function returning True or False and applies it to a sequence, returning a list of only those members of the sequence where the function returned True. A Lambda function can be used with filters.
Let’s say you have to make a list of the squares of integers from 0 to 9 (both included).

>> l = list(range(10))
>> l = list(map(lambda x:x*x, l))

Now, you only require those elements that are greater than 10 but less than 80.

>> l = list(filter(lambda x: x > 10 and x < 80, l))

Easy, isn’t it?

Example

Complete the function fun in the editor below.

fun has the following paramters:

• string s: the string to test

Returns

• boolean: whether the string is a valid email or not

Input Format

The first line of input is the integer N, the number of email addresses.
N lines follow, each containing a string.

Constraints

Each line is a non-empty string.

Sample Input

3
lara@hackerrank.com
brian-23@hackerrank.com
britts_54@hackerrank.com

Sample Output

['brian-23@hackerrank.com', 'britts_54@hackerrank.com', 'lara@hackerrank.com']

Solution Implementation

def fun(email):
    try:
        username, url = email.split('@')
        website, extension = url.split('.')
    except ValueError:
        return False

    if username.replace('-', '').replace('_', '').isalnum() is False:
        return False
    elif website.isalnum() is False:
        return False
    elif len(extension) > 3:
        return False
    else:
        return True
def filter_mail(emails):
    return list(filter(fun, emails))

if __name__ == '__main__':
    n = int(input())
    emails = []
    for _ in range(n):
        emails.append(input())

filtered_emails = filter_mail(emails)
filtered_emails.sort()
print(filtered_emails)