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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Evaluate IP Access Rules
You are given a list of IPv4 access-control rules. Each rule consists of: - an action: allow or deny - a CIDR block such as 192.168.0.0/16 You are als...
Remove minimum invalid mixed brackets
Given a string s containing letters and bracket characters from the set (), [], {}, remove the minimum number of bracket characters so that the result...
Connect next pointers for each tree level
You are given the root of a binary tree where each node has fields left, right, and next (initially null). For every node, set its next pointer to the...
Solve common data-structure and puzzle problems
Solve common data-structure and puzzle problems Solve the following independent problems (language of your choice; assume typical 32/64-bit constraint...
Solve Cache, Window, and Heap Problems
You may be asked to solve multiple algorithmic problems in coding rounds: 1. Frequency-based cache: Implement a cache with get(key) and put(key, value...
Count Similar Photo Groups
You are given n photos labeled 0 to n - 1 and an n x n binary matrix isSimilar. - isSimilar[i][j] = 1 means photo i and photo j are directly similar. ...
Implement greedy decoding and beam search
You are given access to an auto-regressive language model that can score the next token based on a prefix. Assume: - next_logprobs(prefix_tokens) -> M...
Optimize algorithms and validate inputs
Optimize algorithms and validate inputs For a typical medium-difficulty coding task, walk through your approach: enumerate edge cases, justify your in...
Query Machines and Mark Them Offline
This question evaluates competency in interacting with RESTful HTTP APIs, JSON parsing and filtering, automation of operational workflows, resilient e...
Simulate a Turn-Based Two-Player Game
This question evaluates API design, state management, move validation, board representation, and correctness guarantees for a turn-based game simulato...
Check if a word exists in a grid
Given an m×n grid of characters and a string word, determine whether the word can be formed by sequentially adjacent cells (adjacent means horizontall...
Remove nodes with a given value
This question evaluates proficiency in singly linked list manipulation, specifically pointer handling and in-place node removal, and falls under the C...
Solve four OA string/array/matrix/graph tasks
This multi-part prompt evaluates proficiency in core programming competencies: string parsing and character classification, simulation/greedy processi...
Compute max planes shot and session count
Problem 1: Max planes you can shoot before any lands You are given two equal-length arrays: - altitude[i]: the initial altitude of plane i (positive i...
Solve frequency and tree-completeness problems
These two problems evaluate competency in frequency counting and selection algorithms for identifying top-k elements and in binary tree structure anal...
Identify read-only files from permission records
This question evaluates proficiency in parsing and filtering structured data by interpreting Unix-like permission strings and extracting filenames bas...
Implement an in-memory storage with TTL and scans
This question evaluates implementation of an in-memory two-level key->field->value store with TTL semantics, lexicographic scans and prefix filtering,...
Solve 12 coding interview problems
Below are multiple independent coding problems. --- Problem 1: Reduce an integer to 0 with \(\pm 2^i\) You are given a positive integer \(n\). In one ...
Compute BBO and NBBO from order data
You are given a list data of order records. Each record is a 4-tuple: ` (exchange_id, price, quantity, order_type) ` - exchange_id: string/int identif...
Design a data structure to store anagrams
This question evaluates proficiency in data structures and algorithms for string grouping and lookup, testing skills in string manipulation, canonical...