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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

← Citadel

Mid Backend at Citadel

BackendMidOutcome unknown◆ Commonly asked· 2023

Mid backend interview. Pragmatic questions — more real-world than pure puzzles.

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • House robber.
    MidMedium◆ Commonly asked
    #dp
    PracticeLeetCode↗GeeksforGeeks↗
  • Pacific Atlantic water flow.
    MidMedium◆ Commonly asked
    #dfs#grid
    PracticeLeetCode↗GeeksforGeeks↗
  • Search in a rotated sorted array.
    MidMedium◆ Commonly asked
    #binary-search
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Implement a leaderboard API backed by a sorted set.
    MidMedium◆ Commonly asked
    #redis#ranking
    PracticeGeeksforGeeks↗Search↗
  • Build a file-upload service with chunking and resume.
    MidHard◆ Commonly asked
    #streaming#storage
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

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

  • Design a movie-ticket booking system (BookMyShow).
    MidHard◆ Commonly asked
    #oop#concurrency
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • Compare rate-limiting algorithms and their trade-offs.
    MidMedium◆ Commonly asked
    #rate-limit
    PracticeGeeksforGeeks↗Search↗
  • How does a load balancer choose a backend?
    MidMedium◆ Commonly asked
    #networking
    PracticeGeeksforGeeks↗Search↗
  • How does HTTPS/TLS establish a secure connection?
    MidMedium◆ Commonly asked
    #networking#security
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

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

  • Tell me about a time you went above and beyond for a customer.
    Mid◆ Commonly asked
    #customer#star
  • Tell me about a time you failed and what you learned.
    Mid◆ Commonly asked
    #growth#star

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