Validating Email Addresses With a Filter Solution

# 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 [email protected] 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
[email protected]
[email protected]
[email protected]


Sample Output

['[email protected]', '[email protected]', '[email protected]']

### 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)