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How to Solve Count Mentions Per User Problem
Master the Count Mentions Per User LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsMedium#3433
LeetCode ProblemCount Mentions Per User
You are given an integer numberOfUsers representing the total number of users and an array events of size n x 3. Each events[i] can be either of the following two types: Return an array mentions where mentions[i] represents the number of mentions the user with id i has across all MESSAGE events. All users are initially online, and if a user goes offline or comes back online, their status change is processed before handling any message event that occurs at the same timestamp. Note that a user can be mentioned multiple times in a single message event, and each mention should be counted separately.
ArrayMathSortingSimulation
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Problem Breakdown
Understanding the Count Mentions Per User Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
You are given an integer numberOfUsers representing the total number of users and an array events of size n x 3. Each events[i] can be either of the following two types: Return an array mentions where mentions[i] represents the number of mentions the user with id i has across all MESSAGE events. All users are initially online, and if a user goes offline or comes back online, their status change is processed before handling any message event that occurs at the same timestamp. Note that a user can be mentioned multiple times in a single message event, and each mention should be counted separately.
MediumProblem #3433
LeetCodeCount Mentions Per User
Related Topics
ArrayMathSortingSimulation
How Phantom Code Helps
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Examples
# Example 1
Input
numberOfUsers = 2, events = [["MESSAGE","10","id1 id0"],["OFFLINE","11","0"],["MESSAGE","71","HERE"]]
Output
[2,2]
# Example 2
Input
numberOfUsers = 2, events = [["MESSAGE","10","id1 id0"],["OFFLINE","11","0"],["MESSAGE","12","ALL"]]
Output
[2,2]
# Example 3
Input
numberOfUsers = 2, events = [["OFFLINE","10","0"],["MESSAGE","12","HERE"]]
Output
[0,1]
Constraints
1 <= numberOfUsers <= 100
1 <= events.length <= 100
events[i].length == 3
events[i][0] will be one of MESSAGE or OFFLINE.
1 <= int(events[i][1]) <= 105
The number of id<number> mentions in any "MESSAGE" event is between 1 and 100.
0 <= <number> <= numberOfUsers - 1
It is guaranteed that the user id referenced in the OFFLINE event is online at the time the event occurs.
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Solve Count Mentions Per User — You are given an integer numberOfUsers representing the total number of users an...
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Frequently Asked Questions
Common questions about solving Count Mentions Per User and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Count Mentions Per User during interviews?
Phantom Code 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 Count Mentions Per User?
Phantom Code 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 help me communicate my solution for problems like Count Mentions Per User?
Yes. Phantom Code 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 assist with different programming languages for Count Mentions Per User type problems?
Phantom Code 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 help me avoid during Count Mentions Per User interviews?
Phantom Code 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 detectable when solving problems like Count Mentions Per User during live interviews?
No. Phantom Code 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 help when I'm struggling with Count Mentions Per User 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 work for the coding platforms used in Count Mentions Per User interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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