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."
Implement Prefix Search and Node Removal
This interview included two coding tasks: 1. Implement a prefix-search data structure for strings with two operations: insert(word) and count_with_pre...
Maximize Letters from Disjoint Words
This question evaluates understanding of combinatorial selection, set-based constraints, and efficient representation and enumeration of candidate sub...
Find smallest start index avoiding left exit
You are given an integer array jump of length n (0-indexed). If you are currently at index i, your next position becomes i + jump[i] (a positive value...
Implement most frequent key without using max()
You are given the following Python class skeletons. The Parent class precomputes: - self.l: the original list - self.lf: a set of the stringified item...
Build a Quadtree and Analyze a Graph
Solve the following two coding problems. 1. Build a quadtree from an image You are given an N x N matrix of integers representing an image, where N is...
Maximize 1D deliveries within distance and minimize total distance
This question evaluates combinatorial optimization and constrained matching skills, focusing on reasoning about distance-based pairings, lexicographic...
Maximize non-adjacent sum on an N-ary tree
You are given an N-ary tree (each node may have 0..k children). Each node contains an integer value (can be 0 or positive). You want to select a set o...
Compute graph distance and impacted services
This question evaluates proficiency in graph algorithms and traversal (shortest-path/BFS and cycle handling), file-path/tree modeling, dependency grap...
Find cheapest flight with at most K stops
Problem You are given a directed weighted graph representing flights between cities. Inputs - An integer n: number of cities, labeled 0..n-1. - A list...
Implement cloud storage with quotas and compression
Problem Implement an in-memory cloud storage service that supports multiple users, per-user storage quotas, changing quotas with eviction, and file co...
Solve three classic coding problems
These tasks evaluate algorithmic problem-solving, data structure mastery, and implementation skills within the Coding & Algorithms domain, touching on...
Implement a multi-rover Mars controller
Problem Build a small command-line “Mars Rover Controller” program. Single rover (v1) A rover starts at coordinate (0, 0) on an infinite 2D grid and i...
Can the character reach the destination?
You control a character starting at a start cell and want to reach a target cell in a 2D grid. Some cells are blocked by obstacles and cannot be enter...
Implement timestamped task management system APIs
You are implementing an in-memory Task Management System. All API methods are called with a timestamp representing the logical time when the operation...
Solve stock and banana problems
Solve both coding problems below. 1. Maximum single-transaction stock profit: Given an array prices where prices[i] is the stock price on day i, retur...
Implement User Sessionization From Event Stream
You are building a backend data-processing component that consumes a stream of newline-delimited JSON events. Each event represents a user sending a m...
Compute courier pay and implement load balancing
Problem 1: Compute courier (delivery driver) pay You are given a sequence of delivery-related events for a courier during a day. Your task is to compu...
Answer four string/array/battery coding questions
You are given four independent coding questions. Problem A — Uppercase vs lowercase count difference Given a string s (ASCII), count how many characte...
Implement binary encode/decode with frequency tree
Problem Implement a binary encoding and decoding scheme for strings based on character frequencies (Huffman-like coding). You must implement two funct...
Implement an LRU cache
Problem: LRU Cache Design and implement a data structure that supports an LRU (Least Recently Used) cache with a fixed capacity. Requirements Implemen...