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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"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
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Find Words Containing Other Words
This question evaluates string-processing skills, knowledge of substring matching techniques and supporting data structures, and the ability to analyz...
Write SQL for app metrics
You are given a simplified schema for a photo-sharing app: - users(user_id, user_name, joined_at) - photos(photo_id, user_id, created_at) - follows(fo...
Compute days until plants stop dying
You are given a row of plants, each with an integer pesticide level. Rules - On each day, any plant with a strictly greater pesticide level than the p...
Check whether brackets are balanced
This question evaluates a candidate's competency in string processing and bracket-matching concepts, testing familiarity with linear-time algorithms a...
Rebalance shard ranges under overlap limit
This question evaluates skills in interval and range management, constraint enforcement, and algorithmic problem solving related to overlapping intege...
Validate whether a given sequence is a Hamiltonian path
You are given strArr, an array of three strings describing an undirected graph and a proposed vertex visit order: 1. strArr[0]: a comma-separated list...
Find the third-largest word by length
Given an array of strings strArr (length ≥ 3), return the third largest word when ranking words by string length in descending order. Ranking rules: -...
Find all balanced k in a permutation
You are given a permutation \(p\) of length \(n\) containing each integer from \(1\) to \(n\) exactly once. For each \(k\) where \(1 \le k \le n\), de...
Design a data structure for dynamic top‑K frequency
Design a data structure that maintains a multiset of integers and supports the following operations efficiently: Operations - insert(x): Add one occur...
Implement a hash table with put/get
Problem Implement a simplified hash table (hash map) data structure from scratch. Required API Design a class HashTable with: - HashTable(int numBucke...
Schedule prerequisite classes with retakes
This question evaluates competency in graph algorithms, dependency resolution, stateful scheduling, and robust error handling within the Coding & Algo...
Minimize coins with overpay and change
This question evaluates algorithmic optimization and combinatorial reasoning in the coin-change domain, measuring proficiency with efficient numeric m...
Compute a moving average on a stream
This question evaluates understanding of streaming data structures, sliding-window aggregation, and the time/space trade-offs involved in maintaining ...
Merge overlapping 2D line segments
This question evaluates computational geometry and algorithmic skills, specifically collinearity detection, geometric segment intersection, merging of...
Maximize events attended given date ranges
This question evaluates understanding of interval scheduling and efficient algorithm design for allocating limited time-based resources, including con...
Implement retrieval and evaluation for a simple RAG
This question evaluates understanding of embedding-based retrieval, cosine similarity ranking, and retrieval evaluation metrics (Recall@10 and MRR@10)...
Generate NFT metadata and ensure uniqueness
You are implementing an NFT metadata generator. Each NFT is defined by selecting exactly one trait value from each trait category. You must generate a...
Maximize minimum after K decrements
You are given an integer array A of length N and an integer K. You must perform exactly K operations. In each operation, choose any index i and do A[i...
Solve three coding rounds
This multi-part question evaluates algorithmic problem-solving and practical implementation skills, covering grid geometry and distance metrics for ne...
Implement follow graph with snapshots
This question evaluates a candidate's ability to design efficient persistent data structures and versioned state management for time-travel queries in...