Unique Email Addresses — LeetCode 929 Python Solution

The problem

Every valid email consists of a local name and a domain name, separated by the '@' sign. Besides lowercase letters, the email may contain one or more '.' or '+'.

Example

Input

emails = ["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.

Python solution

class Solution:
    def numUniqueEmails(self, emails: List[str]) -> int:
        s = set()
        for email in emails:
            local, domain = email.split("@")
            t = []
            for c in local:
                if c == ".":
                    continue
                if c == "+":
                    break
                t.append(c)
            s.add("".join(t) + "@" + domain)
        return len(s)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 929. Unique Email Addresses is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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