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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Implement TF-IDF scoring for documents
Problem Implement a simplified TF–IDF scorer. You are given: - A list of documents docs, where each document is a string. - A query string q. Tokeniza...
Implement 2D convolution forward pass
Problem Implement the forward pass of a 2D convolution (conv2d) from scratch (no deep learning libraries). You are given: - Input tensor x with shape ...
Implement an LFU cache
Problem: LFU Cache Design and implement a Least Frequently Used (LFU) cache with a fixed capacity. The cache supports the following operations: - get(...
Compute Jaccard similarity between two strings
Jaccard Similarity of Two Strings Given two strings a and b, compute their Jaccard similarity based on token sets. Tokenization rules - Convert to low...
Validate near-palindrome and course prerequisite feasibility
Coding round (40 minutes): two problems You do not need to run code, but you should: - Explain your approach clearly. - Walk through the logic on exam...
Compute party hours per town and city gaps
You are given (1) a region table describing a hierarchy of locations and (2) a list of party attendance time intervals (all timestamps occur within a ...
Implement weighted random city and sparse dot product
Question 1: Weighted random city picker You are given a mapping from city → population (all populations are positive integers). Implement a random gen...
Determine if a string can be segmented
Given a string s and a list of strings wordDict, determine whether s can be segmented into a sequence of one or more dictionary words. - You may reuse...
Compute minimal time to finish dependent tasks
Coding: Task Scheduling With Prerequisites (Parallel Allowed) You have n tasks labeled 1..n. Each task takes exactly 1 unit of time to complete. Some ...
Solve shipping capacity and expression insertion
Problem A: Minimum shipping capacity You are given an array weights where weights[i] is the weight of the i-th package. Packages must be shipped in or...
Convert 32-bit integer to hexadecimal
Problem Given a 32-bit signed integer num, return its hexadecimal representation as a string. Requirements - Use lowercase letters a-f. - Do not inclu...
Return all root-to-leaf path sums
Problem You are given the root of a binary tree where each node contains an integer value (may be negative). Return an array/list containing the sum o...
Assemble DNA payload strings from tagged fragments
You are given a list of DNA-like fragments. Each fragment is a tuple: - start_tag: string - end_tag: string - payload: string A valid DNA chain is for...
Solve two linked list/array tasks
This two-part question evaluates proficiency with fundamental data structures and algorithmic problem-solving—specifically linked list manipulation an...
Find two numbers that sum to a target
Array sum lookup Given an integer array nums and an integer target, find two distinct indices i and j such that: - nums[i] + nums[j] == target - i != ...
Find shortest distance between two islands
Problem You are given an R x C binary grid where: - 1 represents land - 0 represents water The grid contains exactly two 4-directionally connected isl...
Implement sparse matrix addition and multiplication
Implement sparse-matrix operations with explicit error handling. Sparse matrix A matrix A has dimensions r x c and is sparse, meaning most entries are...
Simulate an exchange and participation-rate trading
Implement a simplified trading simulation in three parts. Part 1 — Process market data / exchange interaction (order book) Design a minimal limit-orde...
Implement factorial and count trailing zeros
Answer the following coding questions in Python. 1) Implement factorial Implement a function factorial(n) that returns \(n!\) for a non-negative integ...
Merge two sorted arrays in-place
You are given two integer arrays sorted in non-decreasing order, and two integers m and n: - nums1 has length m + n. The first m elements of nums1 con...