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Interview questions from top companies, mapped to the exact round they show up in. Prep for what you will actually face.

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Online AssessmentDSA / CodingMachine CodingLow-Level Design

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The Loop aggregates publicly shared interview experiences and curated commonly-asked questions, each labeled with its source. Not affiliated with any company listed.

CC BY-NC 4.0 · © 2026

← Costco

Staff+ Full-stack at Costco

Full-stackStaff+Outcome unknown◆ Commonly asked· 2024

A staff fullstack loop. Fast-paced; expect follow-ups that push on depth.

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Rotate array.
    Staff+Medium◆ Commonly asked
    #array
    PracticeLeetCode↗GeeksforGeeks↗
  • Course Schedule — detect a cycle / topological sort.
    Staff+Medium◆ Commonly asked
    #graph#topo-sort
    PracticeLeetCode↗GeeksforGeeks↗
  • Median of two sorted arrays.
    Staff+Hard◆ Commonly asked
    #binary-search
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 1 question

Low-Level Design

Object-oriented / low-level design of a focused module.

  • Design a chess game (pieces, moves, board).
    Staff+Hard◆ Commonly asked
    #oop
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 2 questions

System Design

High-level architecture of a large-scale system.

  • Design a leaderboard for millions of players.
    Staff+Medium◆ Commonly asked
    #redis#ranking
    PracticeGeeksforGeeks↗Search↗
  • Design an accessible internationalized form system.
    Staff+Medium◆ Commonly asked
    #frontend#a11y#i18n
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 1 question

Hiring Manager

Scope, ownership, and role-fit discussion with the manager.

  • How do you run an incident and the postmortem after?
    Staff+◆ Commonly asked
    #reliability#process
05

Round 05 · 2 questions

Behavioral / HR

Values, collaboration, and past-experience (STAR) questions.

  • Describe a goal you set and how you achieved it.
    Staff+◆ Commonly asked
    #ownership#star
  • Tell me about a time you failed and what you learned.
    Staff+◆ Commonly asked
    #growth#star

Practice each round across every company

  • DSA / Coding
  • Low-Level Design
  • System Design
  • Hiring Manager
  • Behavioral / HR

◆ This experience is composed from commonly reported questions for this role and level. Real, individually-shared interviews will be layered in over time.