Used by thousands of developers who passed their interviews
How to Solve Event Emitter Problem
Master the Event Emitter 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
Medium#2694
LeetCode ProblemEvent Emitter
Design an EventEmitter class. This interface is similar (but with some differences) to the one found in Node.js or the Event Target interface of the DOM. The EventEmitter should allow for subscribing to events and emitting them. Your EventEmitter class should have the following two methods:
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 Event Emitter Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
Design an EventEmitter class. This interface is similar (but with some differences) to the one found in Node.js or the Event Target interface of the DOM. The EventEmitter should allow for subscribing to events and emitting them. Your EventEmitter class should have the following two methods:
MediumProblem #2694
LeetCodeEvent Emitter
Related Topics
How Phantom Code AI Helps
Get real-time assistance for Event Emitter problems during coding interviews. Phantom Code AI provides instant solutions and explanations.
Examples
# Example 1
Input
actions = ["EventEmitter", "emit", "subscribe", "subscribe", "emit"], values = [[], ["firstEvent"], ["firstEvent", "function cb1() { return 5; }"], ["firstEvent", "function cb1() { return 6; }"], ["firstEvent"]]Output
[[],["emitted",[]],["subscribed"],["subscribed"],["emitted",[5,6]]]
# Example 2
Input
actions = ["EventEmitter", "subscribe", "emit", "emit"], values = [[], ["firstEvent", "function cb1(...args) { return args.join(','); }"], ["firstEvent", [1,2,3]], ["firstEvent", [3,4,6]]]Output
[[],["subscribed"],["emitted",["1,2,3"]],["emitted",["3,4,6"]]]
# Example 3
Input
actions = ["EventEmitter", "subscribe", "emit", "unsubscribe", "emit"], values = [[], ["firstEvent", "(...args) => args.join(',')"], ["firstEvent", [1,2,3]], [0], ["firstEvent", [4,5,6]]]Output
[[],["subscribed"],["emitted",["1,2,3"]],["unsubscribed",0],["emitted",[]]]
# Example 4
Input
actions = ["EventEmitter", "subscribe", "subscribe", "unsubscribe", "emit"], values = [[], ["firstEvent", "x => x + 1"], ["firstEvent", "x => x + 2"], [0], ["firstEvent", [5]]]
Output
[[],["subscribed"],["subscribed"],["unsubscribed",0],["emitted",[7]]]
Constraints
1 <= actions.length <= 10
values.length === actions.length
All test cases are valid, e.g. you don't need to handle scenarios when unsubscribing from a non-existing subscription.
There are only 4 different actions: EventEmitter, emit, subscribe, and unsubscribe.
The EventEmitter action doesn't take any arguments.
The emit action takes between either 1 or 2 arguments. The first argument is the name of the event we want to emit, and the 2nd argument is passed to the callback functions.
The subscribe action takes 2 arguments, where the first one is the event name and the second is the callback function.
The unsubscribe action takes one argument, which is the 0-indexed order of the subscription made before.
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 Event Emitter — Design an EventEmitter class. This interface is similar (but with some differenc...
Here's the optimal approach using the right algorithm:
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 Event Emitter and using Phantom Code AI during coding interviews.
How does Phantom Code AI help me solve coding problems like Event Emitter 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 Event Emitter?
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 Event Emitter?
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 Event Emitter 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 Event Emitter 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 Event Emitter 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 Event Emitter 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 Event Emitter 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.