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.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"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."
Compute delivery order via BFS
A city road network is an unweighted, undirected graph G(V, E) with a depot node s and D delivery requests located at nodes r1..rD, each with an integ...
Implement an In-Memory Database
Design and implement an in-memory database that stores records by key. Each record is a map from field to integer value. Implement the following funct...
Implement Trie search with wildcard matching
Design a text dictionary using a Trie. Support the following operations: - addWord(word): Insert a lowercase English word. - search(pattern): Return t...
Determine if a multiple-sum subarray exists
Given an integer array nums and an integer k, determine whether there exists a contiguous subarray of length at least 2 whose sum is divisible by k; r...
Count vowel-only substrings with all vowels
Given a lowercase English string s, return the number of contiguous substrings that ( 1) consist only of vowels from the set {a, e, i, o, u}, and ( 2)...
Implement LRU cache with O(1) ops
Design and implement a fixed-capacity cache supporting get(key) -> value and put(key, value) in O( 1) average time. When capacity is reached, evict th...
Calculate Courier Earnings
Design a function to calculate total courier pay from a set of delivery orders. Assume time is represented as integer minutes, and intervals are half-...
Implement a memory allocator with malloc/free
Problem You are implementing a simplified memory allocator over a contiguous memory region. Initialize the allocator with a fixed total size: - alloca...
Implement Kac ring with O(1) color and kstep
You are implementing a Kac ring dynamical system. Model - There are N positions arranged in a circle, indexed clockwise: 0, 1, ..., N-1. - Each positi...
Traverse org chart level by level
Problem You are given an organization chart as manager relationships. Each employee is represented by: - employee_id (string/int) - manager_id (string...
Maximize profit with transaction fee
Given an array of daily stock prices and a fixed transaction fee charged on each sell, compute the maximum profit achievable with any number of buy–se...
Implement log aggregation in React
React Coding: Log stream aggregation You are building a small React feature that displays real-time statistics from a log stream. Log event format Eac...
Solve Several Algorithm Problems
The interview included several coding tasks: 1. Longest symmetric substring: Given a string s, return the longest contiguous substring that reads the ...
Maximize Unique Characters from Words
You are given a list of lowercase English words. Select a subset of the words such that no character appears more than once across all selected words....
Implement K-means clustering from scratch
Task: Implement K-means clustering (from scratch) Write a function to perform K-means clustering on a set of points. Input - A dataset X with shape (n...
Filter Invalid Data Events
You are given a list of data events. Each event contains: - event_id: string - creator_id: string - event_type: string - event_time: Unix timestamp - ...
Parse a protobuf-like schema and answer queries
You are given a single string schema describing message types in a simplified, protobuf-like language. Your task is to parse the schema and support tw...
Implement recent-requests counter
You are designing an in-memory component for a web service that needs to track how many requests ("hits") it has received in the last 5 minutes. Imple...
Compute trigger counts in a DAG
You are given a directed acyclic graph (DAG) that represents trigger dependencies between tasks. - Each node represents a task. - There is exactly one...
Group users by same last K watched movies
You are given a list of users' movie-watching histories. Each user’s history is an ordered list of movie IDs in the order they were watched (earliest ...