Used by thousands of developers who passed their interviews
How to Solve Unique Email Addresses Problem
Master the Unique Email Addresses LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
Phantom Code AI generates complete solutions and debugging hints that you can use while explaining your approach, so you stay calm and in control.
undetectable
real-time
works on major platforms
Start Free for WindowsEasy#929
LeetCode ProblemUnique Email Addresses
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 '+'. 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. Note that this rule does not apply to 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. Note that this rule does not apply to domain names. It is possible to use both of these rules at the same time. 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.
ArrayHash TableString
Phantom Code AI will help you solve this problem in real-time during your interview
Get instant solutions, explanations, and code generation
Problem Breakdown
Understanding the Unique Email Addresses Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
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 '+'. 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. Note that this rule does not apply to 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. Note that this rule does not apply to domain names. It is possible to use both of these rules at the same time. 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.
EasyProblem #929
LeetCodeUnique Email Addresses
Related Topics
ArrayHash TableString
How Phantom Code AI Helps
Get real-time assistance for Unique Email Addresses problems during coding interviews. Phantom Code AI provides instant solutions and explanations.
Examples
# Example 1
Input
emails = ["test.email+alex@leetcode.com","test.e.mail+bob.cathy@leetcode.com","testemail+david@lee.tcode.com"]
Output
2
# Example 2
Input
emails = ["a@leetcode.com","b@leetcode.com","c@leetcode.com"]
Output
3
Constraints
1 <= emails.length <= 100
1 <= emails[i].length <= 100
emails[i] consist of lowercase English letters, '+', '.' and '@'.
Each emails[i] contains exactly one '@' character.
All local and domain names are non-empty.
Local names do not start with a '+' character.
Domain names end with the ".com" suffix.
Domain names must contain at least one character before ".com" suffix.
How Phantom Code AI Helps with LeetCode Problems
Reinforce undetectability, platform compatibility, and real-time assistance to remove any doubt.
1000+
developers use Phantom Code AI
and growing every day
95%
success rate
of users pass their interviews
100%
undetectable
native desktop architecture
Real-time
assistance
instant solutions during interviews
See Phantom Code AI in Action
Watch how Phantom Code AI helps solve LeetCode problems during live interviews
Start Interview
⌘I
Online Round
⌘O
Hide⌘B
Interview
Listening
Think
Solve Unique Email Addresses — Every valid email consists of a local name and a domain name, separated by the '...
Here's the optimal approach using Array:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
Start Over ⌘G
Think & Crack ⌘↵
Undetectability Checklist
Run compatibility test before interviews
Use recommended Zoom version settings
Enable advanced screen capture options
Verify native desktop architecture
Test with screen recording software
Platform Compatibility
Zoom
Supported
Google Meet
Supported
HackerRank
Supported
CodeSignal
Supported
CoderPad
Supported
Teams
Supported
User results and traction
Thousands of developers use Phantom Code AI. Social proof signals that this approach helps real candidates land offers across a range of companies.
Undetectability and technical details
Our native desktop architecture avoids common detection vectors used by browser extensions. We provide a clear checklist so you can run basic checks and confirm the app will be invisible.
Platform compatibility and limitations
We work with Zoom, HackerRank, CodeSignal, CoderPad and other web-based platforms. Check the compatibility note and request a browser link if a specific desktop app is unsupported.
Frequently Asked Questions
Common questions about solving Unique Email Addresses and using Phantom Code AI during coding interviews.
How does Phantom Code AI help me solve coding problems like Unique Email Addresses during interviews?
Phantom Code AI generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Unique Email Addresses?
Phantom Code AI adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code AI help me communicate my solution for problems like Unique Email Addresses?
Yes. Phantom Code AI provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code AI assist with different programming languages for Unique Email Addresses type problems?
Phantom Code AI supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code AI help me avoid during Unique Email Addresses interviews?
Phantom Code AI catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code AI detectable when solving problems like Unique Email Addresses during live interviews?
No. Phantom Code AI runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code AI help when I'm struggling with Unique Email Addresses style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code AI work for the coding platforms used in Unique Email Addresses interviews?
Yes. Phantom Code AI works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
20+ Stealth Features. Zero Detection Cases.
The only AI interview tool with an undetectable desktop overlay, real-time audio listening, and personalized AI responses.