Coding & Algorithms Interview Questions
Practice 3,013 real Coding & Algorithms interview questions for 2026. Coding & Algorithms interview questions for top tech firms like Meta, Amazon, Google, Uber, and TikTok — real questions from actual interviews with detailed solutions — to power your interview preparation. This collection is sharply focused on algorithmic patterns (arrays, strings, sliding windows, trees/graphs, dynamic programming, greedy, two-pointers, and hashing), clean, review-ready code, and the explanation skills that distinguish hires. In 2026 expect familiar medium-to-hard problems plus newer twists: AI-enabled or multi-file coding rounds at some companies, more emphasis on explainability and edge-case reasoning, and occasional real-world performance constraints (streaming, concurrency, memory limits). Interviewers evaluate problem framing, algorithm choice, complexity trade-offs, test-case thinking, and communication under time pressure. Best prep mixes pattern-based practice, timed mock interviews, code-review style polishing, and rehearsed explanations of complexity and tradeoffs. Focus your last-mile prep on writing correct, readable code quickly and on explaining why your solution is robust and efficient for production scenarios.

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"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."
Compute outer boundary of an N-ary tree
You are given the root of a rooted N-ary tree. Each node contains: - An integer value. - An ordered list of children from left to right (0 or more chi...
Implement calculator and graph connectivity
Answer the following coding problems: 1. Implement an arithmetic expression evaluator. Given a string containing non-negative integers, spaces, +, -, ...
Compute max profit with forced trades
Given an array prices where prices[i] is the stock price on day i, solve two related tasks under a forced-trade constraint: (a) Exactly one transactio...
Implement SFT Sample Packing
Implement a preprocessing function for supervised fine-tuning data for an autoregressive language model. You are given a list of tokenized training sa...
Solve Four Coding Assessment Tasks
Complete the following four independent coding tasks. 1. Find the day a cumulative visit target is reached You are given an array visits, where visits...
Schedule batched register operations optimally
Problem You are given a text file that describes batches of register operations (reads and writes) on integer-indexed registers. Your task is to sched...
Build User Journey Path Summary
Implement a function build_summary(logs) -> str that summarizes user journeys as a trie-like path tree. You are given a list of action logs. Each log ...
Solve jump maximization and palindromic path queries
You are given two independent algorithmic problems. --- Problem 1 — Jump game with special destinations (maximize score) You are given an integer arra...
Solve four classic algorithm problems
You are given four independent coding tasks. For each task, implement the required function. --- Problem 1: Zigzag level-order traversal of a binary t...
Implement Composable Range Iterators
Implement an iterator library: range(start, end, step= 1) supporting forward/backward iteration, inclusive/exclusive endpoints, negative steps, and ov...
Implement Binary Search in C++
From scratch in C++, implement binary search over a sorted array to locate a target value. Provide a correct iterative implementation, handle not-foun...
Implement crawler and bracket validator
Implement two tasks: ( 1) Write a function crawl(start_urls, fetch, max_depth, domain_filter) that visits pages starting from the given seed URLs usin...
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...
Compute shortest paths with blocked nodes
Given a graph with nodes and edges and a designated source node s, compute the shortest distance from s to every other node. Some nodes are inaccessib...
Generate Weighted Random NFTs with Updates
You manage k NFT types, each with a positive integer rarity weight w[i]. Implement a minter: constructor(w) builds any needed structures in O(k); mint...
Match alphanumeric patterns in a stream
Given a reference 7–8 character alphanumeric code and four candidate codes, select the exact match as quickly as possible. Design a system that: - Eff...
Compute nearest dashmart distances for queries
You are given an m x n grid where each cell is one of: -1 for a wall (impassable), 0 for a dashmart (a store), and INF = 2^31 - 1 for an empty room. M...
Solve Two OA Algorithm Problems
Problem 1: Maximize Pipeline Throughput A pipeline contains n services connected in series. The overall pipeline throughput is the minimum throughput ...
Implement obstacle-course run statistics
You are given a TypeScript codebase for tracking race results on an obstacle course. - A Course has a fixed number of obstacles. - A Run stores the ti...
Compute Courier Delivery Pay
A delivery platform has a service that can return all orders delivered by a courier. You are given: - courierId: the courier's identifier. - ratePerMi...