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.
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Reverse Linked List Groups
This question evaluates linked list manipulation, pointer/reference management, in-place iterative algorithms, and the ability to enforce O(1) extra s...
Replace Delimited Tokens in a String
This question evaluates string parsing, token recognition, and dictionary lookup competencies for robust text replacement, including handling malforme...
Split Markdown Into Header-Aware Chunks
Implement a function that splits a Markdown document into ordered chunks, where each chunk must not exceed a given size limit. A Markdown header is a ...
Implement Caches, Undo, and Traversal
Solve the following coding tasks. For each task, define clean APIs, implement the core logic, and be prepared to explain time and space complexity. Ta...
Solve path and inventory problems
This question evaluates algorithmic problem-solving skills around numeric robustness and stateful stream processing, specifically testing reasoning ab...
Simulate Plant Infection Spread
This question evaluates graph traversal and grid-based simulation skills, including modeling a 2D grid as a graph, propagation dynamics with obstacles...
Execute TTL Cache Operations with Fetch-on-Miss
Execute TTL Cache Operations with Fetch-on-Miss Implement a pure simulator for a TTL cache. The simulator includes put, get, delete, size, and a deter...
Implement Snapshot Iterator Without Order Guarantees
Design and implement a mutable collection that supports snapshot iteration. The collection stores unique values and supports the following operations:...
Solve several streaming, DAG, and DP tasks
This multi-part question evaluates proficiency in streaming and online algorithms, DAG-based scheduling and parallelism reasoning, and constrained dyn...
Match payments to invoices with fallback rules
This question evaluates a candidate's ability to design robust record-matching logic that handles identifier-based matches, fallback heuristics, and n...
Minimize total factory cost with distance penalties
This question evaluates dynamic programming and sequence optimization skills, focusing on modeling cumulative build costs with adjacency distance pena...
Implement concurrent order-accept/pickup simulator
Concurrent restaurant order + pickup simulator Design and implement a thread-safe simulation for a restaurant that: - Receives incoming orders concurr...
Settle Group Expenses with Transfers
You are given a list of group expense transactions from a trip. Each transaction contains: - payer: the person who paid the full amount. - amount: the...
Implement a Snowflake Query Client
Build a lightweight query client for a Snowflake-like data warehouse. Implement a QueryClient that can: 1. Connect to the warehouse using configuratio...
Implement Game Physics and Block Mining
You are given two independent coding tasks from the same interview category. Solve both. Task A: Flappy-Bird-Style Jump Boundary Function Implement a ...
Validate a Parent-Child Forest
This question evaluates understanding of graph theory concepts—specifically rooted trees, parent-child relationships, cycle detection, and node in-deg...
Estimate expected comparisons in a BST
Estimate expected comparisons in a BST In a particular binary search tree, finding node A takes 1 comparison and finding node D takes 3 comparisons. W...
Implement an Expiring Record Store
Implement a level-based in-memory record store. The store contains records identified by a string key. Each record contains fields, where each field i...
Implement Stock Price Query APIs
You are given an initial collection of stock price records. Each record contains: - symbol: a stock name or ticker string - timestamp: initially a cal...
Implement fast power and k-palindrome
This question evaluates numerical algorithm design and string algorithm skills, focusing on efficient exponentiation with negative exponents and deter...