Twilio Coding Interview Questions
25 Twilio coding interview problems with full optimal solutions — 8 easy, 16 medium, 1 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Twilio interviewer values, and a FAQ section.
Showing 8 problems of 25
- #1easyfoundational
1. Two Sum
Two Sum is Twilio's canonical phone-screen warm-up: given an integer array and a target, return the indices of the two numbers that add up to the target. Twilio's bar is that you name the brute-force, the hash-map tradeoff, and walk through duplicate-value edge cases before coding.
3 free resourcesSolve → - #20easyfoundational
20. Valid Parentheses
Valid Parentheses is Twilio's go-to phone-screen stack question: given a string of brackets, decide if every opener is closed by the correct closer in correct order. The rubric grades whether you reach for a stack immediately and handle the three failure modes (wrong closer, unmatched closer, leftover openers).
3 free resourcesSolve → - #21easyfoundational
21. Merge Two Sorted Lists
Merge Two Sorted Lists is Twilio's linked-list mechanics check: splice two sorted lists into a single sorted list in O(m + n). The dummy-head pattern is mandatory; candidates who special-case the first node are flagged for handling unnecessary edge cases.
3 free resourcesSolve → - #121easyfrequently asked
121. Best Time to Buy and Sell Stock
Best Time to Buy and Sell Stock is Twilio's running-min phone-screen probe: given an array of daily prices, find the maximum profit from a single buy and a later sell. The grading bar is whether you produce the linear single-pass solution, not the O(n^2) double loop.
3 free resourcesSolve → - #206easyfoundational
206. Reverse Linked List
Reverse Linked List is Twilio's pointer-mechanics warm-up: flip a singly-linked list in place and return the new head. The grading bar is whether you write the iterative three-pointer version correctly the first try, with bonus credit for a clean recursive version.
3 free resourcesSolve → - #232easyfrequently asked
232. Implement Queue using Stacks
Implement Queue using Stacks is Twilio's amortized-analysis probe: build a FIFO queue using only stack primitives. The grading bar is whether you reach for the two-stack trick (in-stack + out-stack) and articulate the O(1) AMORTIZED guarantee on pop/peek.
3 free resourcesSolve → - #359easycompany favorite
359. Logger Rate Limiter
Logger Rate Limiter is Twilio's signature rate-limit warm-up: implement shouldPrintMessage(timestamp, message) that returns true iff the message hasn't been printed in the last 10 seconds. Twilio's API-platform interviews use this as the entry point to the full rate-limiter design family. The grading bar is the hash-map approach with O(1) per call.
3 free resourcesSolve → - #706easyfrequently asked
706. Design HashMap
Design HashMap is Twilio's data-structure-from-scratch probe: implement put, get, and remove without using any built-in hash table. The grading bar is the chained-bucket design — modulo-bucket + linked-list-of-(key,value) — with explicit collision handling.
3 free resourcesSolve →