Unique Email Addresses

Problem Description

Given an array of strings emails where we send one email to each emails[i], return the number of different addresses that actually receive mails. The email addresses can have periods and plus signs in the local part that affect how they are processed.

Key Insights

• The local name can have periods (.) removed without changing the address.
• The local name can have everything after the first plus (+) sign ignored.
• The domain name remains unchanged.
• We need to handle both of these rules simultaneously to determine unique email addresses.

Space and Time Complexity

Time Complexity: O(n * m), where n is the number of emails and m is the average length of an email.
Space Complexity: O(n), for storing unique email addresses.

Solution

To solve the problem, we will:

1. Use a set to store unique email addresses.
2. For each email:
   • Split the email into the local and domain parts.
   • Process the local part by removing any periods and ignoring everything after the first plus sign.
   • Combine the processed local part with the domain part and add it to the set.
3. The size of the set will give us the number of unique email addresses.

Code Solutions