PracHub
QuestionsCoachesLearningGuidesInterview Prep
|Home/Coding & Algorithms/Anchorage Digital

Design a dynamic leaderboard with rank queries

Last updated: Jun 16, 2026

Quick Overview

This question evaluates proficiency with dynamic data structures and order-statistics, including maintaining sorted order under updates, deterministic tie-breaking, and analyzing time complexity for rank and top-K operations.

  • medium
  • Anchorage Digital
  • Coding & Algorithms
  • Software Engineer

Design a dynamic leaderboard with rank queries

Company: Anchorage Digital

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: medium

Interview Round: Technical Screen

## Problem: Dynamic Leaderboard You are asked to implement a **leaderboard** that maintains scores for a set of elements (e.g., players/items). Scores can change over time, and you must support efficient ranking queries. ### Data model - Each element has a unique `id` (string or integer). - Each element has a numeric `score` (integer). - Higher score means a better rank. - **Rank 1** is the highest score. - **Ties:** if multiple elements have the same score, break ties by `id` in ascending order (so ordering is total and deterministic). ### Operations to support Implement a data structure (or API) supporting these operations: 1. **Update score** - `update(id, delta)` or `updateTo(id, newScore)` (choose one and clearly document it). - If `id` does not exist, it is created. 2. **Delete element** - `remove(id)` removes the element from the leaderboard. If it doesn’t exist, do nothing. 3. **Get top-K elements** - `topK(k)` returns the `k` highest-ranked element IDs (or `(id, score)` pairs). - If `k` exceeds the number of elements, return all elements. 4. **Get rank of a specific element** - `getRank(id)` returns the 1-indexed rank of `id` under the ordering rules. - If `id` does not exist, return `-1`. ### What to discuss - The time complexity of each operation. - How you would optimize for real-world usage patterns (e.g., frequent updates, frequent top-K queries, many deletes). ### Constraints (assume) - Up to ~1e5 elements. - Up to ~1e5 operations. Define clearly what your `update` operation means (delta vs set), and ensure your design supports all operations correctly.

Quick Answer: This question evaluates proficiency with dynamic data structures and order-statistics, including maintaining sorted order under updates, deterministic tie-breaking, and analyzing time complexity for rank and top-K operations.

|Home/Coding & Algorithms/Anchorage Digital

Design a dynamic leaderboard with rank queries

Anchorage Digital logo
Anchorage Digital
Jan 6, 2026, 12:00 AM
mediumSoftware EngineerTechnical ScreenCoding & Algorithms
19
0
Practice Read
Loading...

Problem: Dynamic Leaderboard

You are asked to implement a leaderboard that maintains scores for a set of elements (e.g., players/items). Scores can change over time, and you must support efficient ranking queries.

Data model

  • Each element has a unique id (string or integer).
  • Each element has a numeric score (integer).
  • Higher score means a better rank.
  • Rank 1 is the highest score.
  • Ties: if multiple elements have the same score, break ties by id in ascending order (so ordering is total and deterministic).

Operations to support

Implement a data structure (or API) supporting these operations:

  1. Update score
    • update(id, delta) or updateTo(id, newScore) (choose one and clearly document it).
    • If id does not exist, it is created.
  2. Delete element
    • remove(id) removes the element from the leaderboard. If it doesn’t exist, do nothing.
  3. Get top-K elements
    • topK(k) returns the k highest-ranked element IDs (or (id, score) pairs).
    • If k exceeds the number of elements, return all elements.
  4. Get rank of a specific element
    • getRank(id) returns the 1-indexed rank of id under the ordering rules.
    • If id does not exist, return -1 .

What to discuss

  • The time complexity of each operation.
  • How you would optimize for real-world usage patterns (e.g., frequent updates, frequent top-K queries, many deletes).

Constraints (assume)

  • Up to ~1e5 elements.
  • Up to ~1e5 operations.

Define clearly what your update operation means (delta vs set), and ensure your design supports all operations correctly.

Submit Your Answer to Earn 20XP

Sign in to leave a comment

Loading comments...

Browse More Questions

More Coding & Algorithms•More Anchorage Digital•More Software Engineer•Anchorage Digital Software Engineer•Anchorage Digital Coding & Algorithms•Software Engineer Coding & Algorithms
PracHub

Master your tech interviews with 8,000+ real questions from top companies.

Product

  • Questions
  • Learning Tracks
  • Interview Guides
  • Resources
  • Premium
  • For Universities
  • Student Access

Browse

  • By Company
  • By Role
  • By Category
  • Topic Hubs
  • SQL Questions
  • AI Coding Questions
  • Compare Platforms
  • Discord Community

Support

  • support@prachub.com
  • (916) 541-4762

Legal

  • Privacy Policy
  • Terms of Service
  • About Us

© 2026 PracHub. All rights reserved.