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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Design adjustable ID allocator
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Implement transactional key–value store
Design and implement an in-memory key–value store that supports transactions and nested transactional blocks. Your system must process a stream of com...
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Find connected region sizes in matrix
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Simulate one-round color elimination on a grid
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Find longest segment with endpoints > interior
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Find minimum days to deliver all orders
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Decide target via subsequence plus/multiply expression
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Rotate matrix and find max lamp coverage
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Compute rightmost-smaller delay times
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Implement expiring credit ledger
Implement an expiring-credit ledger that supports out-of-order events. Expose three functions with the following semantics: - add_credit(id, amount, t...
Implement DFS and tree algorithms
Part 1 (DFS on graph): Given an undirected graph with n nodes labeled 0..n-1 and an edge list, implement a function that returns all connected compone...
Implement expression expansion to plus-only form
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Check inorder subsequence and edit tree minimally
Given a binary tree whose nodes store integers and an array target, determine whether target is a subsequence of the tree's inorder traversal (element...
Find earliest supporting version under constraints
You are given version strings formatted as {major}.{minor}.{patch}, e.g., "103.003.03". Each version either supports a feature or not. You may call is...
Maximize coins collected by 3-step pieces
You are given a 1D board of length N. Each cell is in one of three states: - Empty - Piece (a movable token) - Coin (collectible) In one move, you may...