old_contents: """Leetcode 929. Unique Email Addresses
  Easy
  
  URL: https://leetcode.com/problems/unique-email-addresses/
  
  Every email consists of a local name and a domain name, separated by the @ sign.
  
  For example, in alice@leetcode.com, alice is the local name, and
  leetcode.com is the domain name.
  
  Besides lowercase letters, these emails may contain '.'s or '+'s.
  
  If you add periods ('.') between some characters in the local name part of an
  email address, mail sent there will be forwarded to the same address without
  dots in the local name. For example, "alice.z@leetcode.com" and 
  "alicez@leetcode.com" forward to the same email address.
  (Note that this rule does not apply for domain names.)
  
  If you add a plus ('+') in the local name, everything after the first plus sign
  will be ignored. This allows certain emails to be filtered, for example
  m.y+name@email.com will be forwarded to my@email.com.
  (Again, this rule does not apply for domain names.)
  
  It is possible to use both of these rules at the same time.
  
  Given a list of emails, we send one email to each address in the list.
  How many different addresses actually receive mails? 
  
  Example 1:
  Input: ["test.email+alex@leetcode.com","test.e.mail+bob.cathy@leetcode.com","testemail+david@lee.tcode.com"]
  Output: 2
  Explanation: "testemail@leetcode.com" and "testemail@lee.tcode.com" actually receive mails
  
  Note:
  - 1 <= emails[i].length <= 100
  - 1 <= emails.length <= 100
  - Each emails[i] contains exactly one '@' character.
  - All local and domain names are non-empty.
  - Local names do not start with a '+' character.
  """
  
  class SolutionSplitReplace(object):
      def numUniqueEmails(self, emails):
          """
          :type emails: List[str]
          :rtype: int
  
          Time complexity: O(m*n), where 
            - m is the number of emails,
            - n is the length of email address.
          Space complexity: O(m*n).
          """
          unique_emails = set()
  
          for email in emails:
              # Split email by '@' into local and domain.
              local, domain = email.split('@')
  
              # Remove local's '.'.
              local = local.replace('.', '')
  
              # Truncate local's chars after '+'.
              trunc_local = local.split('+')[0]
  
              # Concat modified local and domain.
              modified_email = '@'.join([trunc_local, domain])
  
              unique_emails.add(modified_email)
  
          return len(unique_emails)
  
  
  def main():
      # Output: 2
      emails = ["test.email+alex@leetcode.com",
                "test.e.mail+bob.cathy@leetcode.com",
                "testemail+david@lee.tcode.com"]
      print SolutionSplitReplace().numUniqueEmails(emails)
  
  
  if __name__ == '__main__':
      main()
  
new_contents: """Leetcode 929. Unique Email Addresses
  Easy
  
  URL: https://leetcode.com/problems/unique-email-addresses/
  
  Every email consists of a local name and a domain name, separated by the @ sign.
  
  For example, in alice@leetcode.com, alice is the local name, and
  leetcode.com is the domain name.
  
  Besides lowercase letters, these emails may contain '.'s or '+'s.
  
  If you add periods ('.') between some characters in the local name part of an
  email address, mail sent there will be forwarded to the same address without
  dots in the local name. For example, "alice.z@leetcode.com" and 
  "alicez@leetcode.com" forward to the same email address.
  (Note that this rule does not apply for domain names.)
  
  If you add a plus ('+') in the local name, everything after the first plus sign
  will be ignored. This allows certain emails to be filtered, for example
  m.y+name@email.com will be forwarded to my@email.com.
  (Again, this rule does not apply for domain names.)
  
  It is possible to use both of these rules at the same time.
  
  Given a list of emails, we send one email to each address in the list.
  How many different addresses actually receive mails? 
  
  Example 1:
  Input: ["test.email+alex@leetcode.com","test.e.mail+bob.cathy@leetcode.com","testemail+david@lee.tcode.com"]
  Output: 2
  Explanation: "testemail@leetcode.com" and "testemail@lee.tcode.com" actually receive mails
  
  Note:
  - 1 <= emails[i].length <= 100
  - 1 <= emails.length <= 100
  - Each emails[i] contains exactly one '@' character.
  - All local and domain names are non-empty.
  - Local names do not start with a '+' character.
  """
  
  class SolutionSplitReplace(object):
      def numUniqueEmails(self, emails):
          """
          :type emails: List[str]
          :rtype: int
  
          Time complexity: O(m*n), where 
            - m is the number of emails,
            - n is the length of email address.
          Space complexity: O(m*n).
          """
          unique_emails = set()
  
          for email in emails:
              # Split email by '@' into local and domain.
              local, domain = email.split('@')
  
              # Remove local's '.'.
              nodot_local = local.replace('.', '')
  
              # Truncate local's chars after '+'.
              trunc_local = nodot_local.split('+')[0]
  
              # Concat modified local and domain.
              modified_email = '@'.join([trunc_local, domain])
  
              unique_emails.add(modified_email)
  
          return len(unique_emails)
  
  
  def main():
      # Output: 2
      emails = ["test.email+alex@leetcode.com",
                "test.e.mail+bob.cathy@leetcode.com",
                "testemail+david@lee.tcode.com"]
      print SolutionSplitReplace().numUniqueEmails(emails)
  
  
  if __name__ == '__main__':
      main()
  
subject: Revise to nodot_local for better var name