Twilio | L3 | Bengaluru [Offer]
Question Details
YoE: 7 Experience: mid & large scale MNCs Date: November, 2024 Round 1 (Coding) Problem 1 /* Design a custom stack structure that supports standard stack operations while efficiently tracking both the minimum and maximum...
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YoE: 7
Experience: mid & large scale MNCs
Date: November, 2024
Round 1 (Coding)
Problem 1
/*
Design a custom stack structure that supports standard stack operations while efficiently tracking both the minimum and maximum elements at any given time. Implement the CustomMinMaxStack class with the following methods:
CustomMinMaxStack() \u2014 Initializes the stack.
void insert(int value) \u2014 Adds an element\'s value to the top of the stack.
void remove() \u2014 Deletes the element currently at the top.
int peek() \u2014 Retrieves the element currently at the top without removing it.
int findMin() \u2014 Fetches the smallest element in the stack.
int findMax() \u2014 Fetches the largest element in the stack.
Each method should operate with a time complexity of O(1).
*/
Note: Working modular code was expected by addressing all the edge cases.
Problem 2
Design a java class that takes requests and sends them to an api endpoint. The class shouldn\'t send the request to the API immediately but batch them once the number of piled requests exceeds a maximum size. One constraint here is that a request can only be held for a max certain duration and once the duration exceeds the request should be sent immediately without waiting for the next batch.
Note: Code was not expected. Discussion happened around approach and how thread & async operations would work here.
Round 2 (Design)
Design an \'Accounts System\' which will be integrated with multiple third party services.
As I understood, this was some existing system in Twilio and interviewer wanted to gauge my approach for it.
Functional Requirement
-Our system will act as a source of truth for any accountId with all relevant account details for an id stored within our system
-Third party services can make read/write requests to this system for any accountId
Note: Requirement was fairly stratight forward. Major discussions happened around API specs, DB choices, scalability, concurrency management.
Round 3 (HM)
Standard behavioural HM rounds. Scenario based mostly and past experiences.
Round 4 (Coding)
Similar to
https://leetcode.com/problems/minimum-knight-moves/description/
Thoughts: Pretty good interview process. HR was super transparent and thoughtful. Rounds were wrapped up within a week. Cumulative feedback was taken post first couple of rounds and then processed further.
Offer: https://leetcode.com/discuss/compensation/6091837/Twilio-or-L3-or-Offer
About This Question
This is a reported interview question from a twilio interview for a eng manager role (junior level) during the phone screen round reported in 2025.
It covers the following topics: Os, Concurrency, System Design, Stack .
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This question was reported by a candidate who interviewed at Twilio. LeakCode aggregates interview reports from 10+ sources, including 1Point3Acres, Glassdoor, LeetCode Discuss, Blind, Reddit, Indeed, and Nowcoder. Each report is translated where necessary, deduplicated against existing entries, and tagged by company, role, round type, and reporting date.
Use this question as one calibration data point, not a memorization target. Companies typically rotate their question pools every 2-4 months; the exact wording of a 2024 question may differ from what you encounter today. The underlying pattern, difficulty level, and follow-up depth at Twilio are the higher-signal extractions to take from this report.
For broader preparation context, the Twilio interview process typically includes a recruiter screen, one or two technical phone screens, and a 4-5 round on-site loop covering coding, system design (at L4+ levels), and behavioral. Reports tagged on LeakCode show the round-by-round distribution and typical difficulty calibration. To browse questions filtered by round type and seniority, use the company hub linked above.
How To Practice This Type of Question
Solve similar problems on LeetCode under timed conditions (25-35 minutes per medium difficulty). The goal is pattern recognition: recognize the underlying technique (sliding window, two-pointer, BFS, memoized recursion, etc.) within 60-90 seconds of reading. Strong candidates verbalize their hypothesis out loud before coding, then iterate based on feedback. Weak candidates dive into implementation immediately, lose time on the wrong approach, and run out of time for follow-ups.
Companies update their question pools every 2-4 months. The exact wording of any given question may have been retired by the time you interview. Focus your prep on the pattern, not the specific problem. The patterns that appear in Twilio reports consistently are the ones worth investing in; one-off niche problems are not.
During Your Twilio Round
Apply the standard interview round template: clarify requirements (2-3 minutes), state your approach out loud and confirm direction with the interviewer (3-5 minutes), code with narration (15-25 minutes), test with concrete examples including edge cases (5 minutes), discuss optimization or trade-offs if time permits (5 minutes). This template is universally accepted across FAANG and adjacent companies; deviating from it produces weaker interviewer feedback signal.
The single most predictive failure mode in Twilio reports tagged "no hire": not asking clarifying questions. Interviewers are explicitly trained to weight this. Strong candidates ask 3-5 clarifying questions even on problems that look obvious; weak candidates dive into code immediately. The clarifying-question check is often the first signal recorded in the interviewer's written notes.