Coding & Algorithms Interview Questions
Practice 3,429 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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Solve three coding interview problems
You are given three independent coding questions. 1) Decode an encoded string Given an encoded string s, decode it using the following rule: - Pattern...
Minimal Unique Word Abbreviations
Minimal Unique Word Abbreviations You are given an array words of n distinct strings. Produce a minimal abbreviation for every word according to the r...
Compute the Minimum Number of Meeting Rooms
Compute the Minimum Number of Meeting Rooms Problem Implement minimumMeetingRooms(intervals) -> rooms. Each interval is a two-element integer array [s...
Validate Sorted Order Under a Custom Alphabet
This question evaluates a candidate's ability to apply custom ordering rules and string comparison logic, a common variant of array and string validat...
Implement permutations and image retrieval
The coding portion included several short exercises for a vision-focused ML role: 1. Given an array of distinct integers, return all possible permutat...
Debug and extend obstacle-run statistics classes
Problem: Obstacle course run statistics (debug + implement) You are building software to track how long racers take to complete an obstacle course. Do...
Solve four coding problems
The interview included four independent coding problems: 1. Longest all-healthy service streak You are given the daily health-check results for mul...
Shortest Path in a Grid with Blocked Cells
This question tests a candidate's practical grasp of graph traversal algorithms applied to 2D grid problems, specifically BFS for unweighted shortest-...
Find Shortest Unique Prefixes
This question evaluates string-processing skills and understanding of data structures for prefix management (e.g., tries), along with algorithmic effi...
Calculate Streaming Token Usage Costs
Calculate Streaming Token Usage Costs Implement a usage calculator for language-model API requests. Input and output tokens have different prices, and...
Build a Versioned In-Memory Database
Build a Versioned In-Memory Database The source reports a four-stage in-memory database exercise but does not provide its exact method signatures. The...
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...
Determine Whether Two Strings Are Isomorphic
Determine Whether Two Strings Are Isomorphic Problem Implement areIsomorphic(source, target) -> result. Two strings are isomorphic when every characte...
Solve stock profit and vertical tree traversal
You have a 60-minute coding interview with two algorithm questions: 1) Max profit from one stock trade - Input: an integer array prices, where prices[...
Build an Expression That Reaches a Target
Build an Expression That Reaches a Target Given a sequence of integers and a target, insert +, -, or * between adjacent numbers and add parentheses so...
Sort Matrix Diagonals By Their Values
Given an n x n matrix of lowercase letters, consider every diagonal that runs from bottom-left to top-right. There are 2n - 1 such diagonals. Assign e...
Compute the Product of an Array Except Self
The interview report preserved the input-output example but not every original restriction. The following is a self-contained version of the reported ...
Implement a Circular Buffer
This question evaluates understanding of data structures and buffer management, specifically FIFO semantics, fixed-capacity storage, wraparound indexi...
Maximize Points by Buying Cost-Multiplier Cards
This question evaluates a candidate's ability to reason about optimal ordering and subset selection under a multiplicative-then-subtractive scoring ru...
Assign meetings to rooms with delays
This question evaluates skill in scheduling algorithms, priority queue and heap usage, greedy decision-making, and time-based event simulation for man...