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 2D transforms and find max-lit point
Part A — 2D array transforms: Given an m×n integer matrix, implement the following in-place operations with clear function boundaries and complexity: ...
Implement round-robin load balancer
Implement a load balancer that distributes incoming requests across N backend servers in strict round-robin order. Requirements: ( 1) Support addServe...
Compute build order from dependencies
Given a set of package build dependencies, output a valid build order so that each package is built only after all of its dependencies. The input is a...
Count islands on a torus grid
You are given an m x n binary grid representing water ( 0) and land ( 1) laid out on a torus: the top edge is adjacent to the bottom edge and the left...
Decide transform via one-to-one mapping
You are given two strings s and t of equal length over the lowercase English alphabet. In one step, you may pick any character x and replace all its o...
Find shortest path using BFS
Given an m×n grid grid where grid[r][c] = 0 represents an empty cell and 1 represents a wall, a start cell (sr, sc), and a target cell (tr, tc), you m...
Compute unique-dasher concurrency with tie-breaking
You are given N delivery assignments, each as (dasherId, startTime, endTime) with 0 <= startTime < endTime. A single dasher may hold multiple overlapp...
Find horizontal cut balancing square areas
Given a 2D table with top-left origin (0, 0), you are provided a finite set of n non-overlapping, axis-aligned square cakes. Each square i has real-va...
Approach verbose data-structure design
For a data-structure design problem whose behavior is easy to understand but whose implementation is lengthy, describe your step-by-step approach: cla...
Simulate 1-D collisions and scale to huge inputs
Given an array of integers representing objects on a 1-D track, where the sign indicates direction (positive moves right, negative moves left) and the...
Compute community ranges and town idle hours
You are given two in-memory datasets for a party-planning app. 1) PartyWindow: {partyId: string, startTime: ISO-8601 UTC datetime, endTime: ISO-8601 U...
Determine sanitized palindrome in string
Write a function that determines whether a string is a palindrome after removing non-alphanumeric characters and ignoring case (e.g., punctuation, whi...
Detect intersection of two linked lists
Given two singly linked lists that may converge to share a common tail, determine whether they intersect and return the first node at which they join....
Find top co-purchased products
You receive purchase logs where each order is represented as an integer array of product IDs bought together in a single transaction. Implement a func...
Compute islands in a binary grid
You are given an m-by-n grid of characters where '1' represents land and '0' represents water. Count the number of connected land masses (islands) usi...
Implement binary search for boundary index
Given a sorted integer array nums (length n) and an integer target t, return the index of the first element in nums that is greater than or equal to t...
Design and implement a bank account system
Design and implement a minimal banking service with the following capabilities: 1) Create bank accounts with unique IDs and an initial balance; suppor...
Find longest unique-character substring
Given a string s, return the length of the longest substring without repeating characters. Explain and implement an O(n) sliding-window solution using...
Solve array modulo and parentheses tasks
Implement two tasks: 1) Count subarrays by modulo remainder - Input: integer array nums (length n), integers K (1 ≤ K ≤ 10^ 4) and R (0 ≤ R < K). - Ou...
Navigate unknown grid to locate target
You control a mouse in an unknown 2D maze. You do not know the maze dimensions or your absolute coordinates. The interface exposes move() → bool (atte...