09 Sept 2026•Easy•Go / Python / TypeScript

Unique Email Addresses

Count distinct destination addresses after applying local-name normalization rules.

Split each address, remove the local part after plus, delete local dots, then combine it with the unchanged domain in a set.

Complexity

O(total characters) time and space.

Solution files

Go•unique-email-addresses/solution.go

package main

import "strings"

func numUniqueEmails(emails []string) int {
	unique := map[string]bool{}
	for _, email := range emails {
		parts := strings.SplitN(email, "@", 2)
		local := strings.SplitN(parts[0], "+", 2)[0]
		local = strings.ReplaceAll(local, ".", "")
		unique[local+"@"+parts[1]] = true
	}
	return len(unique)
}

Python•unique-email-addresses/solution.py

class Solution:
    def numUniqueEmails(self, emails: list[str]) -> int:
        unique: set[str] = set()
        for email in emails:
            local, domain = email.split("@")
            unique.add(local.split("+")[0].replace(".", "") + "@" + domain)
        return len(unique)

TypeScript•unique-email-addresses/solution.ts

function numUniqueEmails(emails: string[]): number {
  const unique = new Set<string>();
  for (const email of emails) { const [local, domain] = email.split("@"); const normalized = local.split("+")[0].replaceAll(".", ""); unique.add(normalized + "@" + domain); }
  return unique.size;
}