Coding & Algorithms Interview Questions
Practice 3,469 real Coding & Algorithms interview questions for 2026. Covers companies like Meta, Amazon, Google, Uber, and Microsoft. Real questions from actual interviews with detailed solutions — ideal for focused interview preparation. Coding & Algorithms interview questions are the single most common technical gate for software engineering roles and are used to evaluate problem framing, algorithm selection, complexity trade-offs, correctness, edge-case reasoning, and clear communication under time pressure. Expect this category to appear in early technical screens and repeatedly across onsite loops at companies that weight it heavily (notably Meta, Google, and Amazon). Interviews will test arrays and strings, trees and graphs, dynamic programming, hashing and two‑pointer techniques, and the candidate’s ability to test and optimize code in a shared editor. Prepare with timed mock interviews, practice in the same editor you’ll use live, and build a progressive schedule that moves from fundamentals to medium/hard problems; typical candidates invest several weeks to a few months of focused practice depending on seniority and target company.
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"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."
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"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."
Solve three algorithmic OA tasks
Solve three algorithmic OA tasks Task 1 (Odd-frequency string): Given an integer N in [1..200000], write an algorithm that returns any length-N string...
Infer the Smallest Valid Character Order from Sorted Password Hints
Infer the Smallest Valid Character Order from Sorted Password Hints You are given password hints already sorted according to an unknown alphabet. Infe...
Content Safety Filter
This coding question tests string parsing, tokenization logic, and pattern-matching algorithm design in a practical content moderation context. It eva...
Solve interval, grid-fill, and heap tasks
You are asked to solve the following algorithmic problems. Problem 1: Concurrent users from online intervals You are given n inclusive time intervals ...
Find a secret word using match feedback
This question evaluates algorithmic problem-solving, combinatorial reasoning, and information-theoretic search strategies for narrowing a secret from ...
Build a Wordle-style game in React
Task Implement a simplified Wordle-style game as a small React app. No styling/CSS is required (plain HTML output is fine). Game rules (assume Wordle-...
Find fair split of a two-color necklace
Given a circular necklace represented by a string s over {'a','b'}, you may cut the necklace at most twice (yielding three contiguous pieces). Can you...
Account Balance with Expiring Grants
This question evaluates the ability to design a data structure that tracks time-limited credit grants, prioritizing expiration order during spending a...
In-Memory Key-Value Database with Nested Transactions
This question evaluates a candidate's ability to design a data structure that layers transactional state over a committed base, testing skills in nest...
Design an n x n Tic-Tac-Toe Game
This question evaluates a candidate's ability to design a class-based data structure that tracks game state and efficiently detects a win condition af...
Deep Equality of Two Records
This coding question tests a software engineer's ability to implement recursive structural comparison across nested, heterogeneous data types. It eval...
Compute and plot a precision–recall curve
You are given model outputs for a binary classifier: - y_true: an array of 0/1 ground-truth labels of length n. - y_score: an array of predicted score...
Write SQL to rank top products per category
You are given two tables: products - product_id (int, primary key) - category (string) order_items - order_id (int) - product_id (int) - quantity (int...
Solve linked list, tree, and grid problems
Problem A — Find cycle entry in a singly linked list You are given the head of a singly linked list. The list may contain a cycle. - Return the node w...
Minimum Canisters to Top Up an Exact Target
This question evaluates a candidate's grasp of dynamic programming, specifically the unbounded knapsack (coin change) pattern for finding the minimum ...
Deterministic Task Execution Order
This question evaluates a candidate's ability to model task dependencies as a directed graph and produce a valid execution order, a core graph algorit...
Implement a search autocomplete suggestion service
This question evaluates proficiency in designing efficient prefix-matching and ranking mechanisms, including management of incremental query state and...
Calculate Transaction Fees
You are building a payment processor. Each transaction has an amount in cents, a payment type, and a payment status. The platform charges a percentage...
Compute transaction fees from a CSV string
You are given a CSV string representing a list of payment transactions. Write a function that parses the CSV and returns a CSV string with the total p...
Identify the Extra Directed Edge
You are given a list of directed edges edges, where each edge is represented as [parent, child]. The graph contains nodes labeled from 1 to n, and it ...