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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"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."

"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."

"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Analyze Python Functions: Improve Readability and Efficiency
Scenario Zoom interview code-review segment: interviewer shares three short Python functions used in a data-science pipeline. Question Walk through th...
Compute balances, rejections, and platform reserve
You are given a set of transactions in CSV-like format with columns: - account_name, timestamp, currency, amount Assume: - Transactions for all accoun...
Construct a circular gift exchange across families
You are given a “big family” composed of several sub-families. Each sub-family is a list of unique person IDs/names. Example input: - [[A1, A2], [B1, ...
Resolve user roles across account hierarchy
You are given: 1. An account hierarchy: `json accounts = [ {"accountId": "org_1", "parent": null}, {"accountId": "wksp_1", "parent": "org_1"} ] ` ...
Solve grid shortest-path and tree DP
Problem A — Shortest path in a maze (BFS) You are given a 2D grid representing a maze: - grid[r][c] is either '.' (open cell) or '#' (wall). - You are...
Count three-digit numbers with distinct digits
Problem Given two integers left and right such that 100 ≤ left ≤ right ≤ 999, count how many three-digit integers x in the inclusive range [left, righ...
Solve linked list reversal and minima problems
You are given three independent coding tasks. 1) Reverse a singly linked list Input: The head of a singly linked list. Output: The head of the same li...
Design a weighted random value generator
Weighted random value generator Design a generic component that stores values with integer weights and can return a random value with probability prop...
Find available reservation time slots
Problem You are building an API to show which time slots are available for booking at a restaurant. You are given: - The restaurant’s opening hours (p...
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 Python LRU cache with args and persistence
Implement an LRU cache in Python as a decorator or class that correctly supports variable-length positional arguments and keyword arguments. Ensure th...
Check carpool trip feasibility
You are given a list of trips where each trip i is (passengers_i, start_i, end_i) with start_i < end_i on a one-dimensional route. A single vehicle wi...
Design a versioned key-value store
Design and implement a versioned key-value store that supports set(key, value, timestamp) and get(key, timestamp) to retrieve the most recent value at...
Solve BFS grid delivery routing
You are given an m×n grid representing a city: 'S' are DashMart stores, 'H' are homes, '.' are roads, and '#' are obstacles. Movement is allowed in fo...
Check diagonal equality in a matrix
Given an m x n integer matrix, determine whether every top-left to bottom-right diagonal contains identical values (all elements along each such diago...
Compute shortest recursive string encoding
Given a string s, compress it by replacing any consecutive repetition of a substring with the form k{pattern} where k > 1 and pattern may itself be re...
Implement weighted-eviction cache
Question Design and implement a weighted cache supporting get(key) and put(key, value, weight) operations. The cache has a total weight limit; when in...
Minimize cost & recommend movies
Question Given arrays size[] and cost[] where size[i] is the size of the i-th product and cost[i] is the cost to increase size[i] by one unit, compute...
Remove elements to avoid k-prefix duplicates
Question Given two lists listA and listB and an integer k, delete elements from listB so that the first k elements of the new listB share no value wit...
Find exit URL via BFS API calls
Question Design and implement a function that, given a starting URL "/", performs BFS or DFS by repeatedly sending HTTP GET requests of the form GET "...