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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Implement 2048 Game Logic
Implement the core movement logic for the 2048 game. You are given an n x n integer board where 0 represents an empty cell and every nonzero value rep...
Implement a Recipe Cart
You are building a shopping cart for a cooking app. The system is initialized with: - A recipe catalog: each recipe_name maps to a list of ingredients...
Implement topological sort and tree boundary traversal
You are given two separate coding tasks. Problem A — Order courses with prerequisites You have n courses labeled 0..n-1 and a list of prerequisite pai...
Implement IP Address Arithmetic
Implement an IP address utility library. Support the following operations: 1. Parse an IPv4 address in dotted-decimal form, such as 192.168.0.1. 2. Gi...
Count White Balls After K Steps
You are given a ring of N positions indexed from 0 to N-1. - At each position i, there is initially one ball whose color is either white or black. - E...
Design rolling-window conversation score tracker
Design a class that tracks conversation scores over a rolling time window. Requirements You are given a window size W (in seconds) at initialization t...
Implement Game Metadata Lookups
You are given a list of game metadata records. Build an in-memory representation that can store each game's name, release date, platforms, genre, publ...
Implement Connect Four with bottom push-up
Implement a Connect Four variant with bottom push-up. In standard Connect Four a dropped disc falls to the lowest empty cell of a column. In this vari...
Multi-Agent Collision Simulator (Unicycle Kinematics)
Multi-Agent Collision Simulator (Unicycle Kinematics) You are given $N$ agents moving in a 2D plane. Each agent is a disk of fixed radius and moves ac...
Implement a Circular Buffer
Implement a fixed-capacity circular buffer. A circular buffer stores elements in insertion order, supports removal of the oldest element, and reuses s...
Maximize Throughput and Count Trigger Components
You are given two independent coding problems. Problem 1: Maximize Pipeline Throughput A production pipeline has n services connected in series. Servi...
Implement Tail and Find Monster Cost
This entry contains two coding tasks from the same interview category. Task A: Implement a file tail operation Implement a function tail(filePath, n) ...
Compare Complete and Partial Poker Hands
Implement a simplified poker-hand comparator. You are given two poker hands. A complete hand contains exactly 5 cards. Each card has a rank and, if ne...
Least Frequently Used (LFU) Cache
Least Frequently Used (LFU) Cache Design and implement a data structure for a Least Frequently Used (LFU) cache that supports get and put operations i...
Course Schedule Feasibility
Course Schedule Feasibility You are registering for numCourses courses, labeled 0 to numCourses - 1. Some courses have prerequisites: before you can t...
Caesar Cipher with Translation-Table Optimization
Implement a Caesar cipher. Given a string text and an integer shift, return a new string in which every alphabetic character is rotated forward by shi...
Detect and Break a Cycle in a Singly Linked List
You are given the head of a singly linked list. The list may or may not contain a cycle: somewhere in the list, one node's next pointer may point back...
Implement Table Aggregation
You are given a table represented as a list of rows. Each row contains: - key: a string identifying a group - value: an integer Write a function that ...
Search Words in a Character Grid
You are given a 2D grid board of lowercase English letters with m rows and n columns. A word can be constructed from letters of sequentially adjacent ...
Implement a Snapshot Set Iterator
Design and implement a set data structure that supports snapshot iteration. The set stores unique values. It must support the following operations: - ...