Coding & Algorithms Interview Questions

Practice 3,469 real Coding & Algorithms interview questions for 2026. Covers companies like Meta, Amazon, Google, Uber, and Microsoft. Real questions from actual interviews with detailed solutions — ideal for focused interview preparation. Coding & Algorithms interview questions are the single most common technical gate for software engineering roles and are used to evaluate problem framing, algorithm selection, complexity trade-offs, correctness, edge-case reasoning, and clear communication under time pressure. Expect this category to appear in early technical screens and repeatedly across onsite loops at companies that weight it heavily (notably Meta, Google, and Amazon). Interviews will test arrays and strings, trees and graphs, dynamic programming, hashing and two‑pointer techniques, and the candidate’s ability to test and optimize code in a shared editor. Prepare with timed mock interviews, practice in the same editor you’ll use live, and build a progressive schedule that moves from fundamentals to medium/hard problems; typical candidates invest several weeks to a few months of focused practice depending on seniority and target company.

3.5k Questions 368 Companies08.11.2026
Showing 20 results
Role
Anthropic logo
Anthropic
Medium
Software Engineer

Implement a Banking System

Design and implement an in-memory banking system. All operations are processed in non-decreasing timestamp order. Account identifiers are strings. Mon...

Coding & Algorithms
9
0
67 people solved
May 24, 2026
Roblox logo
Roblox
Medium
Data Scientist

Optimize bread-factory pipeline for max profit

You can assemble a production line by choosing modules of three types: Mixers, Ovens, Packers. Each module i has (type, build_cost_i, throughput_i uni...

Coding & Algorithms
8
0
118 people solved
Oct 13, 2025
Google logo
Google
Medium
Software EngineerIntern Locked

Match people to questions using tags and priorities

This question evaluates competencies in bipartite matching and combinatorial optimization, along with practical data-structure design for scalable tag...

Coding & Algorithms
11
0
189 people solved
Dec 27, 2025
Peregrine logo
Peregrine
Medium
Software Engineer

Fetch, group, and print paginated activities

Fetch, group, and print paginated activities Given a paginated API that returns (totalCount, activities[]) for a requested page, implement code that i...

Coding & Algorithms
13
0
126 people solved
Aug 4, 2025
Snowflake logo
Snowflake
Medium
Software Engineer

Solve Array Distance and Wiki Navigation

You are given two independent coding tasks. For each task, clarify edge cases, implement the function, and write meaningful test cases. Task 1: Minimu...

Coding & Algorithms
2
0
27 people solved
Apr 23, 2026
DoorDash logo
DoorDash
Medium
Software Engineer

Maximize Chef Assignment Profit

You are given three integer arrays: - chefSkill[i]: the skill level of the i-th chef. - dishDifficulty[j]: the difficulty level required to cook the j...

Coding & Algorithms
2
0
20 people solved
Apr 23, 2026
Citadel logo
Citadel
Medium
Software Engineer

Make Every Password Block a Palindrome

Implement minimum_palindromic_block_changes(password, k). The password length is a multiple of k. Partition it into consecutive blocks of exactly k ch...

Coding & Algorithms
0
0
4 people solved
Mar 27, 2026
DoorDash logo
DoorDash
Medium
Software Engineer

Implement image carousel with comments and upvotes

Implement an image carousel that supports: 1) cycling forward/backward and autoplay with a configurable interval; 2) a per-image comment thread with c...

Coding & Algorithms
5
0
81 people solved
Sep 6, 2025
Meta logo
Meta
Medium
Software Engineer

Merge Three Sorted Arrays Without Duplicates

Merge Three Sorted Arrays Without Duplicates You are given three integer arrays sorted in nondecreasing order. Merge them into one sorted array that c...

Coding & Algorithms
0
0
11 people solved
Mar 2, 2026
Anthropic logo
Anthropic
Medium
Software Engineer

Find Duplicate Files

Implement a file deduplication tool. You are given a root directory containing many files. Return groups of duplicate files. Two files are duplicates ...

Coding & Algorithms
12
0
80 people solved
Mar 2, 2026
Flexport logo
Flexport
Hard
Software Engineer

Measure Meeting Coverage and Required Rooms

Measure Meeting Coverage and Required Rooms Given meeting intervals, compute both the total amount of time spent in at least one meeting and the minim...

Coding & Algorithms
0
0
8 people solved
Jun 28, 2026
Uber logo
Uber
Medium
Software EngineerSenior+

Quadtree for 2D Geospatial Points

Quadtree for 2D Geospatial Points Design and implement a point quadtree that stores geographic locations on a 2D plane and supports efficient axis-ali...

Coding & Algorithms
0
0
6 people solved
Jun 28, 2026
Uber logo
Uber
Medium
Software EngineerSenior+

Group Anagrams

Group Anagrams Given an array of strings words, group together all strings that are anagrams of one another and return the groups. Two strings are ana...

Coding & Algorithms
1
0
10 people solved
Jun 28, 2026
Meta logo
Meta
Medium
Data Engineer Locked

Write queries for follows and bookings

This question evaluates the ability to manipulate temporal event logs, enforce bidirectional relational integrity, and implement efficient graph and i...

Coding & Algorithms
25
1
174 people solved
Mar 1, 2026
Box logo
Box
Medium
Software Engineer

Design out-of-order windowed stream processor

Design out-of-order windowed stream processor Design an event processor for an unbounded, infinite stream of events. Each event has the fields id, tim...

Coding & Algorithms
16
0
268 people solved
Aug 1, 2025
SoFi logo
SoFi
Medium
Software Engineer

Implement a multithreaded task executor with semaphores

Design and implement a thread-safe TaskExecutor that limits concurrent work using a semaphore-like mechanism. You are given an interface similar to: -...

Coding & Algorithms
11
0
119 people solved
Feb 4, 2026
Anthropic logo
Anthropic
Medium
Software Engineer

Convert stack samples to trace events

Question Implement convertToTrace(samples) that, given a chronologically ordered vector of stack samples (each sample contains a timestamp and a call-...

Coding & Algorithms
181
2
676 people solved
Jul 29, 2025
Optiver logo
Optiver
Medium
Software Engineer

Build and Validate a Binary Tree from Parent-Child Pairs

Build and Validate a Binary Tree from Parent-Child Pairs You are given a single input string that is supposed to describe a binary tree as a sequence ...

Coding & Algorithms
1
0
16 people solved
Apr 21, 2026
Scale AI logo
Scale AI
Medium
Software Engineer Locked

Implement a Task Processor

This question evaluates understanding of priority-based scheduling and dependency resolution, focusing on data structures and graph-ordering concepts ...

Coding & Algorithms
30
0
256 people solved
Feb 27, 2026
Meta logo
Meta
Hard
Data Engineer

Write SQL for car rental utilization by city

SQL / Data Query Prompt (Car Rental) You are given four tables: user - user_id location - location_id - city car - car_id - car_size (e.g., compact, m...

Coding & Algorithms
12
2
183 people solved
Dec 1, 2025

Frequently Asked Questions

How difficult are Coding & Algorithms interview questions?
Difficulty spans a wide range: from quick easy warm-ups to multi-stage hard problems that require advanced data structures or algorithmic proofs. Most companies place a majority of live coding rounds at the medium level, with occasional hard questions used to distinguish senior candidates. Interviewers evaluate problem framing, algorithm choice, time/space complexity, clean implementation, and thoughtful testing under time pressure. Expect more conceptual depth at Google, more consistent medium-to-hard screens at Meta, and Amazon to mix coding with leadership signals. Leveling depends on role and seniority: entry-level focuses on fundamentals; senior roles emphasize design, optimizations, and tradeoffs.
Where does Coding & Algorithms appear in a typical interview loop, and which companies weight it most heavily?
Coding & Algorithms is usually the first technical hurdle: it appears in phone/online screens, followed by one or more onsite or virtual coding rounds during the loop. Typical sequences are a technical screen, two to three in-loop coding sessions, then system design or behavioral rounds. Companies that weight this category heavily include Google, Meta, and Amazon, where coding performance often determines whether you progress. Candidates commonly concentrate practice for weeks or months beforehand; most targeting large tech firms prepare intensively for 6–12 weeks, while some spend 3–6 months for deeper mastery or level changes.
How long should I prepare and how should I structure that preparation?
Plan focused, progressive practice over a realistic timeline. A practical structure is an 8–12 week block: weeks 1–2 solidify fundamentals and language fluency; weeks 3–6 target core patterns (arrays, trees, graphs, DP) with timed problem sessions and pattern tagging; weeks 7–9 emphasize mock interviews, end-to-end problem solving, and optimization tradeoffs; final weeks simulate real loops with full-length sessions and targeted weak-point drills. Candidates with less experience may extend to 12–16 weeks. Regularly review mistakes, practice communicating solutions aloud, and include at least one weekly mock interview with peer or coach feedback.
What key subtopics and patterns should I master for Coding & Algorithms interviews?
Master a consistent set of patterns and their variations: arrays and strings (two pointers, sliding window), hash maps and frequency counts, sorting and binary search, recursion and backtracking, dynamic programming, trees and traversals, graphs (BFS/DFS, shortest paths, union-find), heaps and priority queues, and greedy algorithms. Also practice complexity analysis, space-time tradeoffs, and writing bug-resistant code with tests. For higher levels, focus on amortized analysis, advanced graph algorithms, segment trees or Fenwick trees, and system-aware optimizations. Interviewers value reusable problem templates and the ability to generalize patterns to new prompts.
What are standout tips and common pitfalls to avoid in Coding & Algorithms interviews?
Start by clarifying requirements and constraints, then outline your approach before coding. Write a correct, readable baseline solution first, then iterate to improve complexity while narrating tradeoffs. Test with simple and edge cases, and handle nulls, off-by-one, and empty inputs explicitly. Communicate continuously; silence looks like confusion. Avoid premature optimization, overcomplicating solutions, or ignoring interviewer hints. Time management matters: if stuck, discuss alternate approaches and code a partial solution. Finally, practice mock interviews to reduce anxiety and build the habit of clear, structured explanations under pressure.

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