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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Compute peak parking lot occupancy intervals
You are given logs from a parking lot system. Each log entry has the form: [carId, time, eventType] - carId is an integer identifying a car. - time is...
Evaluate variables in simple arithmetic DSL
You are given a small DSL (domain-specific language) consisting of variable assignments, one per line. Each line has the form: `text <identifier> = <e...
Implement string reduction and time map
In a coding interview, you are asked to solve two algorithm problems. 1. String reduction with adjacent duplicates - Basic version: Given a string ...
Assign 2n Workers to Two Tasks to Minimize Total Time
You manage 2n workers and two tasks, A and B. Every worker must be assigned to exactly one task, and each task must be staffed by exactly n workers. W...
Implement JSON parsing and HTTP integration tasks
This question evaluates proficiency in JSON parsing, file I/O, HTTP client integration, request/response handling, payload construction, mapping data ...
Implement sin(x) with precision constraints
Coding Question: Implement sin(x) Implement a function that returns an approximation of the trigonometric sine function. Function signature - Input: a...
Find longest substring without repeating characters
Problem Given a string s, return the length of the longest contiguous substring that contains no repeated characters. Input - s: a string (may contain...
Implement Fibonacci with efficiency constraints
Write a function fib(n) that returns the nth Fibonacci number (0-indexed: fib(0)=0, fib(1)=1). Requirements: - Handle n up to at least 10^6. - Discuss...
How do you expand nested placeholders in strings?
You are given a dictionary of string templates. Keys are identifiers like X, Y, Z. A template may contain placeholders of the form %KEY%, which should...
Count permutations with exactly n inversions
You are given two integers m and n. Consider all permutations of the array [1, 2, ..., m] (each number from 1 to m appears exactly once). A permutatio...
Implement a versioned recipe management system
You are asked to implement an in-memory Recipe Management System (similar in difficulty to a simple banking/in-memory DB exercise). The system support...
Count same-color squares in a character grid
You are given a 2D grid (matrix) of characters. Each character represents a color: cells with the same character are considered the same color. Formal...
Implement course scheduling and rate limiter analysis
You are given two independent coding problems. --- Problem 1: Course Scheduling You are planning to take a set of courses and are given prerequisite r...
Compute moving average over last N stream
You are given an integer N and an unbounded stream of integers arriving one by one. After each new integer arrives, output the average of the last N i...
Count connected land components in a grid
You are given a 2D grid of characters where: - '1' represents land - '0' represents water A group of land cells forms an island if they are connected ...
Find two numbers that sum to target
Given an integer array nums of length n and an integer target, return the indices (i, j) (0-based) of two distinct elements such that nums[i] + nums[j...
Build blog UI with API data and likes
You are asked to implement a small single-page web application in JavaScript (you may use any modern framework or plain JavaScript) to display and int...
Implement sqrt and parity-based array rearrangement
You are given two independent coding tasks. --- Task 1: Implement Square Root Without Math Library Implement a function that computes the square root ...
Compute probability of random arithmetic progression triple
You have the integers from 1 to 30 inclusive. You randomly choose 3 distinct numbers without replacement, and all 3-element subsets are equally likely...
Implement a basic pivot table with totals
You are given a small in-memory table of data and are asked to implement a simplified pivot table operation and a printer for it. Assume the input dat...