Validating Email Addresses With a Filter Solution

You are given an integer  followed by  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.
• The website name can only have letters and digits.
• The maximum length of the extension is .
  
  

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  to  (both included).

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

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

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

Easy, isn't it?

Input Format

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

Constraints

Each line is a non-empty string.

Output Format

Output a list containing the valid email addresses in lexicographical order. If the list is empty, just output an empty list, [].

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 in Python

def fun(s):
    try:
        user, www = s.split("@")
        web, ext = www.split(".")
        if not user or not web or not ext:
            return False
        return not any([user != "".join(filter(lambda x: x.isalnum() or x in ["_", "-"], user)),
            web != "".join(filter(lambda x: x.isalnum(), web)) , len(ext)>3])
    except:
        return False

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)