Coding & Algorithms Interview Questions
Practice 2,960 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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Choose the Best Travel Mode
You are given a 2D grid representing a map, a start cell, a destination cell, and several transportation modes. Each mode has a per-step time cost and...
Reverse Nodes in K-Sized Groups
Given the head of a singly linked list and an integer k, reverse the nodes of the list in contiguous groups of size k. Requirements: - Only complete g...
Solve Seven Python Image and Data Tasks
You are given a Python 3 online assessment with seven independent coding tasks. For each task, implement a function named solution with the specified ...
Solve Two Robbery Optimization Variants
You are asked to solve two related optimization problems. Part 1: Linear street You are given an array values, where values[i] is the amount of money ...
Find Shortest Covering Substring
Given two strings source and target, find the shortest contiguous substring of source that contains every character from target, including duplicate o...
Solve Tree Columns And Maze Variants
Answer the following coding tasks from the interview. 1. Binary-tree column grouping: Given the root of a binary tree, group node values by vertical c...
Minimize Boys Needed Beside Girls
You are given a row of seats in a kindergarten classroom, represented by a string seats. - G means the seat is occupied by a girl. - - means the seat ...
Implement a TTL LRU Cache
Design and implement an in-memory bounded cache with per-entry expiration and LRU eviction. The cache stores uint32_t keys and std::string values. Eac...
Implement an LFU Cache
Design and implement a Least Frequently Used cache. The cache has a fixed positive capacity and supports the following operations: - get(key): Return ...
Check Whether a String Is Built by Repetition
Given a non-empty string s, determine whether it can be constructed by repeating one of its non-empty proper substrings two or more times. A proper su...
Find the Unique Element in Pairs
You are given a sorted integer array nums. Every value appears exactly twice, except for one value that appears exactly once. Find and return the valu...
Implement Minesweeper and Word Search
Solve the following coding problems. Problem 1: Generate and Print a Minesweeper Board You are given integers rows, cols, and mineCount. Generate a ro...
Implement Store Autocomplete
You are given a list of store names, for example: `text ["McDonald's", "KFC", "Burger king", "Bites", "Biscuit shop"] ` Implement an autoComplete(s) m...
Implement EMA Crossovers and Root Solvers
Solve the following coding and algorithmic problem-solving tasks. Task 1: Compute exponential moving average crossovers You are given a pandas DataFra...
Evaluate an Arithmetic Expression
Implement an expression evaluator for a simplified calculator. Given a string s, return the integer value of the expression. The expression may contai...
Compute Jaccard Similarity for Lists
Implement a Python function to compute the Jaccard similarity between two lists of strings. `python def jaccard_similarity(a: list[str], b: list[str])...
Implement Cache, Undo, and DFS
Answer the following independent coding prompts. 1. Timed cache: Implement a generic in-memory cache. Each inserted item has a fixed expiration time k...
Solve Tree View and Triplet Sum
You are asked to solve two coding problems. Problem 1: Return the nodes visible from the right Given the root of a binary tree, return the values of t...
Find the First Unique IP
You are processing a chronological stream of server hit records. Each record contains an IP address as a string. Design and implement a component that...
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...