Coding & Algorithms Interview Questions
Practice 3,429 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."
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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."
Convert Stack Samples into Trace Events
Convert Stack Samples into Trace Events The source reports converting sampled call stacks into trace events but does not provide the exact tuple forma...
Restore an Array with One Displaced Element
Restore an Array with One Displaced Element An integer array was originally sorted in nondecreasing order. It was then changed by removing at most one...
Implement an Integer Spreadsheet with Formulas
Implement an in-memory integer spreadsheet with literals, additive formulas, nested references, replacement updates, and zero-valued unset cells. Each...
Find the Minimum Edge Score on a Path Between Two Cities
Find the Minimum Edge Score on a Path Between Two Cities An undirected road network contains n cities numbered from 1 through n. Each road is represen...
Largest Subset With Positive Bitwise AND
Problem Implement largest_positive_and_subset(nums). Choose a nonempty subset of the given nonnegative integers. The subset is valid when the bitwise ...
Compute the Median After Each Stream Insertion
Compute the median after every insertion into an integer stream without repeatedly sorting the full prefix. Practice maintaining balanced data structu...
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: - ...
Detect Recent Duplicate Records with Bounded Memory
Detect Recent Duplicate Records with Bounded Memory A time-ordered stream contains records [id, text, title, timestamp]. Detect records whose exact (t...
Find A Threshold-Limited Path With Minimum Required Safety
You are given an undirected graph with n nodes, a list of weighted edges, a start node, an end node, and a safety threshold. Each edge has a safety co...
Implement string formatting and request tracking tasks
This multi-part question evaluates string manipulation, numeric formatting, character-mapping validation under 180° rotation, and event-tracking/order...
Implement a Byte Pair Encoding (BPE) Tokenizer
This question evaluates practical understanding of tokenization algorithms and string processing, specifically the iterative merge-based approach used...
Check Whether Two Strings Are Anagrams
Problem Implement are_anagrams(a, b). Return true exactly when a and b contain the same lowercase English letters with the same multiplicities, possib...
Implement an in-memory SQL-like table
Implement a simplified in-memory SQL-like database for a single table. You should support the following operations on a table with a fixed schema (a l...
Settle debts with minimal transactions
You are given a list of debts among a set of people, expressed as triples (debtor, creditor, amount) (equivalently (payer, payee, amount)), where each...
Implement buffered file writer with concurrency support
You are given a simple file writer class that writes data directly to disk: `cpp class FileWriter { public: // Append data to the file on disk imm...
Aggregate Recent Message Events And Active Chats
Prepare for a stateful event aggregation coding prompt over chat events and active chats in a rolling five-minute window. The question is useful for d...
Remove Duplicate Letters Lexicographically
Remove Duplicate Letters Lexicographically Given a lowercase string, remove repeated occurrences so that every distinct letter appears exactly once. T...
Group Events by an Ordered Attribute List
Group Events by an Ordered Attribute List Problem Implement groupEventCounts(fieldNames, events, groupBy) -> resultJson. Each row in events is a porta...
Three Array Problems for Trading Geometry and Grouping
Problem Implement solve(prices, numbers, people, group_size) and return an object with three fields. 1. max_profit: the maximum profit from buying onc...
Advance Cyclic Ball Flips Efficiently
Determine ball colors after many synchronized marker moves around a circle, where marked positions flip before advancing. Derive an O(n + m) parity so...