Coding & Algorithms Interview Questions
Practice 2,950 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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Find viewing direction that sees most points
You are standing at the origin on a 2D plane. You are given a list of points points[i] = (xi, yi) (not necessarily distinct), and a viewing angle thet...
Solve several streaming, DAG, and DP tasks
You were asked multiple algorithmic questions. 1) Streaming longest subarray with average S You receive an infinite stream of integers (can be positiv...
Assign meetings to rooms with delays
You are given: - An integer n (number of meeting rooms, labeled 0..n-1). - A list of m meetings meetings[i] = [start_i, end_i) with start_i < end_i. A...
Shuffle array using random integer API
You are given an array nums of length n representing a deck of distinct cards. You do not have access to a built-in shuffle function, but you are give...
Find maximum value in huge text file
You are given the path to a very large text file on disk. The file has the following properties: - Each line contains exactly one signed 64-bit intege...
Implement Linear Regression Training
Implement a function train_linear_regression(X, y, lr, epochs) that trains a linear regression model from scratch using batch gradient descent. Requir...
Find a valid course order from prerequisites
You are given numCourses labeled from 0 to numCourses-1 and a list of prerequisite pairs prerequisites, where each pair [a, b] means you must complete...
Count ordered fragment pairs forming a password
You are given: - A target string password. - A list of N string fragments fragments[0..N-1] (fragments may repeat). Count the number of ordered pairs ...
Check if all substrings are dictionary words
You are given a string s (letters only) and access to an English dictionary dict (a set of valid words). Return true if every contiguous substring of ...
Design an Editable Text Buffer
The interview question was asked in three progressive stages. Design an in-memory text editor. 1. Basic text buffer Implement a data structure that ...
Implement stream line reader and settle balances
Part 1: Streaming line reader from chunked source You are given an existing class ChunkSource with a method nextChunk() that returns the next piece of...
Check palindrome and find next larger palindrome
Problem: Palindrome Check + Next Larger Palindrome Part 1: Palindrome validation Given a string s, determine whether s is a palindrome (reads the same...
Implement weighted random choice
Implement a simplified version of np.random.choice without calling the built-in function. You are given an array items of length n and an optional pro...
Implement lazy unique-merge generator for sorted streams
Write a Python generator merge_unique(a, b) that lazily merges two nondecreasing iterables a and b (potentially infinite) into a single nondecreasing ...
Find list pair with maximum overlap
You are given N labeled lists of items as a Python dict mapping list_name -> iterable of strings. Example input: {'L1': ['A','B','C'], 'L2': ['A','C',...
Count distinct island shapes in a grid
Problem You are given an m x n grid of integers where 1 represents land and 0 represents water. An island is a group of horizontally or vertically adj...
Count ordered pairs that concatenate to target
Given a list of integers numbers and an integer target, count the number of ordered pairs (i, j) with i != j such that concatenating numbers[i] follow...
Maximize watch time under adjacency constraint
You are given a sequence of videos in a feed. - Input: - An integer array duration[1..n], where duration[i] is the length of video i in seconds. -...
Find next greater element for subset
You are given two integer arrays query and nums. - All elements in nums are distinct. - Every element in query also appears in nums. For each value x ...
Implement multi-part cost calculator
You are given a price catalog and a list of orders. Implement the following in any language (Python examples acceptable): Inputs - price_catalog: mapp...