Coding & Algorithms Interview Questions
Practice 2,960 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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Analyze sales with groupby
You are given three pandas DataFrames representing a food delivery marketplace: - orders(order_id, product_id, quantity, unit_price, status) - product...
Aggregate loans and match repayments
You are building a loan servicing tool. You are given two datasets. Part 1: Aggregate raw loan records Each raw loan record has the following fields: ...
Implement Validation and String Compression
Implement the following two coding tasks. 1. CSV dataset validation You are given: - a multiline string representing CSV data; - a set of banned words...
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...
Solve Two String Problems
You are asked to solve the following two coding problems: 1. Unique Morse Code Transformations You are given an array of lowercase English words, word...
Find Duplicate Files by Content
You are given a list of directory descriptions. Each description has the following format: root_directory file_name_1(content_1) file_name_2(content_2...
Optimize trade PnL table updates
You are asked to modify an existing class without changing its public API: `python class Table: def __init__(self, filters, times): pass ...
Solve two string DP/hash problems
Solve the following two coding questions. 1) Unique Morse Code Transformations You are given an array of strings words (lowercase English letters). Us...
Compute conflicts and minimum meeting rooms
You are given a list of meeting room booking requests. Each request is a half-open time interval [start, end), meaning it uses the room starting at st...
Implement Plurality and Runoff Voting
You are given a list of ballots for an election. Each ballot is an ordered list of distinct candidate names, from highest preference to lowest prefere...
Solve multiple algorithmic interview questions
Below are several independent coding tasks. For each task, implement a function that returns the required output. Assume: - Arrays/lists are 0-indexed...
Maintain a Streaming Median
You are designing a component that receives integers one at a time and must return the current median after each update. Example: - After processing [...
Implement matrix transpose and KV store
The phone screen for a Linux-oriented software engineering role included multiple coding tasks: 1. Transpose an n x n matrix Given a square matri...
Validate KYC CSV Records
Implement a function that validates business-verification records from a CSV-formatted string. - The first line is a header with exactly 6 comma-separ...
Solve Search Speed and String Product
You are asked to solve two coding problems. Problem 1: Find the Minimum Constant Processing Speed You are given an array piles, where piles[i] is the ...
Find minimum time to cross bridge with flashlight
A group of people must cross a bridge at night with one flashlight. The bridge can hold at most two people at a time. - If two people cross together, ...
Estimate Two Conditional Win Probabilities by Simulation
Estimate Two Conditional Win Probabilities by Simulation You are given a game with three closed doors, labeled 0, 1, and 2. Behind exactly one door is...
Implement Prefix Search and Node Removal
This interview included two coding tasks: 1. Implement a prefix-search data structure for strings with two operations: insert(word) and count_with_pre...
Solve binary-tree reverse printing and LPS
You are given a binary tree node definition: - TreeNode { int val; TreeNode left; TreeNode right; } Answer the following two algorithmic questions. 1)...
Validate alternating checkout/return logs
Given a chronological list of events logs of the form (timestamp, book_id, is_checkout) where is_checkout is True for a checkout and False for a retur...