Coding & Algorithms Interview Questions
Practice 3,013 real Coding & Algorithms interview questions for 2026. Coding & Algorithms interview questions for top tech firms like Meta, Amazon, Google, Uber, and TikTok — real questions from actual interviews with detailed solutions — to power your interview preparation. This collection is sharply focused on algorithmic patterns (arrays, strings, sliding windows, trees/graphs, dynamic programming, greedy, two-pointers, and hashing), clean, review-ready code, and the explanation skills that distinguish hires. In 2026 expect familiar medium-to-hard problems plus newer twists: AI-enabled or multi-file coding rounds at some companies, more emphasis on explainability and edge-case reasoning, and occasional real-world performance constraints (streaming, concurrency, memory limits). Interviewers evaluate problem framing, algorithm choice, complexity trade-offs, test-case thinking, and communication under time pressure. Best prep mixes pattern-based practice, timed mock interviews, code-review style polishing, and rehearsed explanations of complexity and tradeoffs. Focus your last-mile prep on writing correct, readable code quickly and on explaining why your solution is robust and efficient for production scenarios.

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Solve four coding problems
The interview included four independent coding problems: 1. Longest all-healthy service streak You are given the daily health-check results for mul...
Solve meeting and tree problems
The interview included two coding tasks: 1. Merge meeting intervals You are given a list of meeting intervals [[start, end], ...], not necessarily ...
Solve Reported OA Coding Problems
The post describes several algorithm questions from an online assessment. The concrete problems that can be reconstructed are: 1. Remove Blocks in a G...
Build a Weekly Calendar
Implement an interactive weekly calendar UI. Requirements: - Display a one-week calendar with 7 days. - The calendar should be divided into 1-hour tim...
Evaluate variables in simple arithmetic DSL
You are given a small DSL (domain-specific language) consisting of variable assignments, one per line. Each line has the form: `text <identifier> = <e...
Generate the next lexicographic array arrangement
Question Given an integer array nums (which may include negative numbers and duplicates), modify nums in place to produce the next arrangement in lexi...
Reorder Search Results for Provider Diversity
Build a function that paginates ordered provider listings for a telehealth marketplace. Each input record is a CSV string in the format: provider_id, ...
Design a circular queue data structure
Problem Design and implement a fixed-capacity circular queue that supports constant-time operations. A circular queue stores elements in an array of s...
Implement Nested Transactional Key-Value Store
Implement an in-memory key-value store that processes a batch of commands, one command per line. The store must support nested transactions. Supported...
Solve peak element and unique word abbreviation
You are given two independent coding problems to solve. 1) Peak element in an array (binary search) - Input: an integer array nums of length n >= 1. -...
Implement time-versioned KV store with restore
Design and implement an in-memory key–value store where every operation is associated with a timestamp (monotonically increasing integer). The store m...
Find the nth prime number
Given an integer n (1-indexed), return the n-th prime number (e.g., n=1 -> 2, n=2 -> 3, n=3 -> 5). Design an algorithm that is efficient for moderatel...
Find valid split-stay listing combinations
You are building a feature that suggests a split stay: a guest stays in one home for the first part of a trip, then switches to a second home for the ...
Implement simple VM manager with CRUD operations
You are asked to implement a simple in-memory virtual machine (VM) manager that can: - List all VMs - Add (create) a new VM - Modify (update) an exist...
Generate Synthetic Clickstream Data with Python Function
Scenario The analytics team needs to generate synthetic click-stream records to test a new reporting pipeline before real traffic arrives. Question Wr...
Evaluate an arithmetic expression
Write a function that evaluates a mathematical expression given as a string. Requirements: - Supports non-negative integers and whitespace. - Supports...
Find top/bottom-k words in list or stream
You are given words (strings) either as a finite list or as an unbounded stream. 1) List version: Given an array words and an integer k, return: - the...
Find High-Intensity Time Periods
Given a list of time-series readings, where each reading is {timestamp, intensity}, and a numeric threshold, return all maximal time periods during wh...
Implement a Parallel Image Processor
You are building a batch image-processing utility. Implement a function that receives a list of jobs. Each job contains: - input_path: the source imag...
Explain OS processes, threads, and memory
Explain core operating system concepts: processes vs threads, context switching, and scheduling (preemptive vs cooperative and common algorithms). Des...