929. Unique Email Addresses

Link: Unique Email Addresses

Thought

Brutal Force Solution
This question is pretty simple (and it actually is an esay one). A naive approache is, split the name and domain.

For the name, remove every thing after first ‘+’, and then replace all ‘.’ as empty. For the domain, just keep it is.

Then, use a set to make sure every thing is unique. After processed all emails, count the length of the set.

Code

class Solution:
    def numUniqueEmails(self, emails):
        """
        :type emails: List[str]
        :rtype: int
        """
        hist = set()
        cnt = 0
        for email in emails:
            name, domain = email.split('@')
            name = name.split('+')[0]
            name=name.replace('.', '')
            if name + '@' + domain not in hist:
                hist.add(name+'@'+domain)
                cnt += 1
        return cnt

Runtime

Time: O(n)
Space: O(n)