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."
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"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."
Validate word abbreviation and reconcile two abbreviations
Validate word abbreviation and reconcile two abbreviations Implement a function isValidAbbreviation(word: string, abbr: string) that returns true if a...
Find first unique character
Find first unique character Given a lowercase/uppercase alphanumeric string s, return the index of the first character that appears exactly once; if n...
Design Efficient Multi-Level Access Control System
Scenario Multi-level access control lists (country → city) must be queried quickly. Question Design and implement a permission system where each geogr...
Maximize Non-Overlapping Task Scheduling Efficiency
Scenario Job scheduler on a single machine wants to maximise throughput. Question Given tasks with [start, end) times, return the maximum number of no...
Implement Data Structure for Top-K Elements in Streams
Scenario Analytics feature that must constantly report the K largest numbers seen so far. Question Implement a data structure that ingests a stream of...
Implement Sampling and Minimize Loss in Numerical Coding
Scenario Numerical coding challenges on sampling and loss minimization. Question a) Implement functions to sample from truncated normal distributions ...
Maximize Distinct Purchases Within Budget Constraints
Scenario Given a customer budget and a list of product prices, determine the maximum number of distinct products the customer can afford. Question Des...
Determine If Two Strings Are Anagrams Efficiently
Scenario Backend service needs to verify whether two user-provided strings are anagrams for text-matching features. Question Implement a Python functi...
Merge Two Insertion Diffs in Linear Time
A text-editing system represents changes to a document as insertion diffs. An insertion diff is a set of (position, value) pairs, where each pair mean...
In-Memory Key-Value Database with Nested Transactions
In-Memory Key-Value Database with Nested Transactions Implement an in-memory key-value database that processes a sequence of commands and supports nes...
Constant-Time Insert, Remove, and Uniform Random Sampling
A data-sampling service maintains a dynamically changing pool of integer example IDs. Examples are continuously added and retired, and the service mus...
User Activity Analytics: Unique Users per Activity and Average Time on Site
User Activity Analytics You are given a collection of records, where each record captures a single user's action on a website. Each record is a dictio...
Median, Variance, and Linear Trend of a Daily Temperature Dataset
Median, Variance, and Linear Trend of a Daily Temperature Dataset You are given n daily temperature readings collected in New York City. The data is a...
Fill Missing Time-Series Values with Linear Interpolation (Duplicate Timestamps Allowed)
Fill Missing Time-Series Values with Linear Interpolation (Duplicate Timestamps Allowed) You are given readings from a single sensor as a list of reco...
Solve prefix, array, and string problems
This set of problems evaluates proficiency in string and array algorithm design—covering prefix search, subsequence matching, and maximal-area computa...
Find Most Frequent Values
Given an integer array nums and an integer k, return the k distinct values that occur most frequently in nums. The result may be returned in any order...
Determine Reachability in Train Schedule
You are given a train schedule represented as a list of train routes. Each route is a list of station names, where the element at index t is the stati...
Implement sampling and subarray scan
A coding interview included the following algorithm questions: 1. You are given access to a function rand01() that returns an independent sample from ...
Implement IPv4 and CIDR iterators
This question evaluates understanding of IPv4 addressing and CIDR notation, along with competency in binary/bitwise arithmetic, iterator construction,...
Count super-streak segments in an event stream
You are given a time-ordered sequence of events. Each event has: - type, a string or integer event type. - ts, an integer timestamp in milliseconds or...