Dataford
Interview QuestionsInterview GuidesExperiencesMock InterviewsPricing
Get started
Dataford
Popular roles
Software EngineerData AnalystData ScientistData EngineerBusiness AnalystAI EngineerMachine Learning EngineerProduct Manager
Browse
Browse All RolesEvery role hub, from analyst to MLBrowse All CompaniesCompany-specific interview loopsAll Interview GuidesThe full guide library
Top questions by role
Software EngineerData AnalystData ScientistData EngineerBusiness AnalystAI EngineerMachine Learning EngineerProduct Manager
Top questions by skill
SQLPythonStatisticsMachine LearningA/B TestingSystem DesignGenerative AIProduct SenseMetricsBehavioral
Browse all questions →Try a mock interview
Experiences
Practice
Mock InterviewsTimed interview simulations with feedbackCoaching1:1 coaching with people at your target companiesSuccess PathYour 6-week structured planModulesCurated lessons by topicWebinarsTalks from ex-Big Tech data leadsPlaygroundA free-form scratch editor
Learn
BlogInterview strategy and career adviceTech Job Market ReportHiring trends across data and AI rolesFor UniversitiesDataford for career centersAbout DatafordWho we are and how we build
Pricing
Build my plan
O(1) Randomized Set
00:00
5 left

O(1) Randomized Set

MediumPython

Problem

Turo may need an in-memory set of active vehicle or trip identifiers where inserts, removals, and random sampling are all fast. Implement a RandomizedSet supporting each operation in average O(1) time.

The set must reject duplicate inserts, report whether deletions succeed, and return a uniformly random element from the current set. The data structure should not use a separate random-selection list that requires scanning or shifting elements during deletion.

Formal Specification

Implement these methods:

  1. insert(value) returns True if value was added, otherwise False.
  2. remove(value) returns True if value was present and removed, otherwise False.
  3. getRandom() returns one uniformly random value currently in the set. This method is called only when the set is non-empty.

value is an integer. For automated testing, implement run_randomized_set(operations), which executes operation arrays such as ["insert", 10], ["remove", 10], and ["getRandom"], returning the results in order.

Constraints

  • 1 <= operations.length <= 10^5
  • -10^9 <= value <= 10^9
  • Each value is an integer
  • getRandom is called only when at least one value exists
  • Random output is checked for membership, not a fixed sequence

Function Signature

def run_randomized_set(operations):
Interviewer

Your question is O(1) Randomized Set. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

You need to log in / sign up to run or submit.
CodePython 3
Sign up free to run your codeLog inLn 2
Run your code to see test output here.