#graphs

119 graphs interview questions, asked at Google, Amazon, Meta and 22 more companies. Last asked Oct 2026.

Work queue with a dead-letter queue and dependency cycle detectionCodingBuild an in-memory work queue for pipeline tasks that depend on each other (download, then tokenize, then train). Workers call nextready() to take a task and report back with…
Last asked Oct 2026
Minimum time to finish dependent steps run in parallelCodingA job is split into n steps numbered 0 to n - 1; step i takes durationsi minutes. A pair u, v in dependencies means step u must finish before step v starts. Any number of steps…
Last asked Oct 2026
Find every recipe you can make from your suppliesCodingYou have an unlimited stock of some basic supplies and a book of recipes. Each recipe has a unique name and a list of ingredients; an ingredient can be a supply, the name of…
Last asked Oct 2026
+1
Reachability in a time-indexed train scheduleCodingGiven train departures and arrivals with timestamps, decide whether a destination is reachable from a start station without time travel. Reported on 1point3acres' Glean bank;…
Last asked Oct 2026
Follow one-way links to the endpoint or the last node before a loopCodingA network has nodes joined by one-way links, and each node links to at most one other node. Starting from a given node, follow the links and return the endpoint: the last node the…
Last asked Oct 2026
+2
Concurrent same-host web crawlerCodingImplement a web crawler that finds every page reachable from a start URL on the same host, and fetches pages concurrently. You are given a blocking helper: Write: python def…
Last asked Oct 2026
Count ordered routes that visit one shop of each of four typesCodingYou need four things from four kinds of shop: a bookshop, a school-supply shop, a sports store and a stationery store. The town has many shops of each kind, joined by roads…
Last asked Oct 2026
Parse message definitions and compute their sizesCodingParse text definitions of message types made of typed fields, where a field can be another message type. Report each field's type and each message's total size from given…
Last asked Sep 2026
Design a work-together distance between two employeesML designDesign a distance d(u1, u2) between any two people in a company that measures how closely they work together: smaller means closer. Decide which signals to use (shared documents…
Last asked Sep 2026
Evaluate divisionCodingYou get equations a / b = value between string variables, each standing for a positive real number, and a large batch of queries c / d. Answer every query from the equations, or…
Last asked Sep 2026
Transitive synonym groups from word contextsCodingGroup words into synonym sets where sharing a four-word context links them transitively. Reported on 1point3acres' Glean bank; reconstructed in our own words.
Last asked Sep 2026
+4
Group dependent tasks into parallel levelsCodingYou run a build system. Each task has a unique, non-empty lowercase name. Some tasks depend on others: a dependency before, after means before must finish before after can start…
Last asked Sep 2026
Effective privileges in a role hierarchy with allow and disallow listsCodingYou are building the access-control layer of a data platform. Every role has: - allowed: privileges granted directly to the role - disallowed: privileges explicitly taken away…
Last asked Sep 2026
Build reporting trees from employee-manager pairsCodingYou get a list of employee, manager pairs, where each person is a positive integer id and the pair means the employee reports directly to that manager. Build the org chart…
Last asked Sep 2026
Unit conversion ratio queries with modular answersCodingYou have n units, numbered 0 to n - 1, split into separate families: units in one family convert into each other, units from different families never do. You are given conversion…
Last asked Sep 2026
Explore a friend graph through a remote API with few callsCodingYou cannot read a social graph directly; the only access is getfriends(userid), a remote call that returns a user's friends and costs a network round trip. Write code that…
Last asked Sep 2026
Lexicographically smallest topological orderCodingGiven tasks and the dependencies between them, return an order that runs every task after the tasks it depends on. When several tasks are ready at once, always pick the smallest…
Last asked Sep 2026
+1
Earliest time everyone is connectedCodingA time-sorted log has lines such as t3 Bob shared-ride-with Charlie. Sharing a ride connects two riders, and connection carries through other riders. Given the log and the list of…
Last asked Sep 2026
Shortest path, nodes on any shortest path, and can Alice evade BobCodingYou get an undirected, unweighted graph with n nodes. Alice starts at node a and wants to reach node t. 1. Return the length of the shortest path from a to t. 2. Return every node…
Last asked Sep 2026
Order dependent tasks and find what must rerunCodingGiven tasks and their prerequisites, return any valid order to run them, or detect that the dependencies form a cycle. Then, given a set of tasks that changed, find every task…
Last asked Sep 2026
Exchange rate between two currencies through chained conversionsCodingYou get a list of rates from, to, rate, each meaning one unit of from is worth rate units of to. Given a source and a target currency, return the rate between them by chaining…
Last asked Sep 2026
+1
Friend recommendation by mutual friendsCodingRecommend friends ranked by number of mutual friends in a social graph. Reported on 1point3acres' Fireworks AI bank; reconstructed in our own words.
Last asked Sep 2026
Shortest increasing path to a target value in a gridCodingGiven an integer grid, answer repeated queries. Each query names a target value; return the values along a shortest path from the top-left cell to a cell holding that value, where…
Last asked Sep 2026
Fewest edge moves to connect a graphCodingAn undirected graph has n nodes and a list of edges. One move detaches an existing edge and reattaches it between any two distinct nodes. Return the fewest moves needed to make…
Last asked Sep 2026
Fewest clicks between two wiki pagesCodingWiki pages link to other pages. Given a start page and a target page, return the fewest clicks needed to get from one to the other, or report that the target can't be reached. You…
Last asked Sep 2026
Fewest nodes on a path when one vertex may be brokenCodingFind the path between two nodes of a graph that passes through the fewest nodes, and return that count. One vertex may be broken and unusable: handle both the case where it…
Last asked Sep 2026
Validate a hierarchy and compute how long a message takes to spreadCodingGiven manager-report relationships, first check that they form a valid hierarchy (one root, no cycles, everyone reachable). Then, if passing a message down each link takes a known…
Last asked Sep 2026
+1
Alien dictionaryCodingYou get a list of words sorted in the dictionary order of an unknown alphabet. Derive an order of the letters that is consistent with it, or report that none exists. Explain how…
Last asked Aug 2026
Smallest valid task order from dependenciesCodingThere are n tasks numbered 0 to n - 1, done one at a time, and a list of pairs a, b meaning a must finish before b starts. Return an order that respects every dependency; among…
Last asked Aug 2026
Can two ordered sequences be merged into one order?CodingYou get two arrays of integer labels. Each array sets ordering rules: a label must come before every label that follows it in the same array. Decide whether one ordering exists…
Last asked Aug 2026
Minimum broadcast latency between citiesCodingCities are linked by network connections, each with a latency. A broadcast starts from a source city and travels along the links. Compute the shortest latency from the source to…
Last asked Aug 2026
Dependency-safe deletion orderCodingEntities have parent-child relationships, and the relationships limit what can be deleted when. Model the relationships as a graph and return an order that deletes everything…
Last asked Aug 2026
Services that go down when their dependencies shut downCodingYou get a map of which services depend on which, and a list of services being shut down. A service is unavailable if it is shut down itself or depends, directly or through other…
Last asked Aug 2026
Dependency-aware concurrent tool schedulerCodingBuild a scheduler that runs a set of tool calls concurrently while respecting their dependencies: a call starts only after every call it depends on has finished, and independent…
Last asked Aug 2026
Count simple paths whose labels match a prefixCodingEvery node of a graph carries a label. Count the simple paths (paths that never repeat a node) whose sequence of labels matches a given prefix string. Explain how you prune the…
Last asked Aug 2026
Is there an island of exactly size k?CodingGiven a grid of land and water, answer many queries of the form "is there an island of exactly k cells?". Find the islands once, then answer each query quickly, and discuss what…
Last asked Aug 2026
Evaluate variable definitions with forward references and cyclesCodingA list of assignments defines variables with arithmetic expressions that may use variables defined later. Evaluate them all, then report which ones are undefined because they…
Last asked Aug 2026
Players whose rank is fixed by game resultsCodingThere are n players, numbered 0 to n - 1, and a list of game results where a pair (u, v) means player u beat player v. Assume the results come from one strict ranking, so there…
Last asked Aug 2026
Course schedule: finish every course and find an orderCodingYou have n courses and a list of prerequisite pairs. 1. Decide whether every course can be completed. This fails exactly when the prerequisites contain a cycle. 2. Return one…
Last asked Jul 2026
Count clusters of 2D points within a radiusCodingTwo points belong to the same cluster when they are within a given distance of each other, and clusters chain through shared neighbors. Given the points and the distance, count…
Last asked Jul 2026
Repair a looping bootloader programCodingA tiny bootloader stores its program as a list of text instructions. Each entry has the form "<op <value", where value is a signed integer. The machine has one accumulator, which…
Last asked Jul 2026
+1
Distance from every desk to its nearest bathroomCodingAn office floor plan is a grid of bathrooms, desks and open floor. For every desk, return how many steps (up, down, left, right) it takes to reach the closest bathroom. Expect…
Last asked Jul 2026
Is a graph bipartite?CodingGiven an undirected graph, decide whether its nodes can be colored with two colors so that no edge joins two nodes of the same color. Color with BFS or DFS and look for a…
Last asked Jul 2026
Reach a target when you can only step between nearby pointsCodingYou get a set of unordered points, a start point, an end point, and a function getDistance(x, y). You can step from one point to another only when their distance is within a…
Last asked Jul 2026
Fewest road reversals in a directed networkCodingA road network has one-way roads. Travelling a road against its direction counts as a violation. Find a route between two given cities with as few violations as possible.
Last asked Jul 2026
Count connected friend groupsCodingGiven people and the friendships between them, count the friend groups: two people are in the same group when they are friends, directly or through a chain of friends. Solve it…
Last asked Jul 2026
Alien dictionary with the smallest valid orderCodingYou get a list of words (password hints) that is sorted under an unknown alphabet. Work out an order of the characters that is consistent with that sorting, and when several…
Last asked Jun 2026
Deterministic task execution orderCodingGiven tasks and their dependencies, return an order to run them that respects every dependency and comes out the same every time for the same input, by a fixed rule for breaking…
Last asked Jun 2026
Alien dictionary: check sorted order, then infer the alphabetCoding1. You are given the order of letters in an unfamiliar alphabet and a list of words. Return whether the words are sorted according to that alphabet. 2. Now the alphabet is…
Last asked Jun 2026
Three-color map coloringCodingYou are given a map as a list of location names, locations, and a list of pairs, adjacencies. Each pair a, b means locations a and b share a border. Implement colormap(locations…
Last asked Jun 2026
Minimum triggers to clear linked balls on a gridCodingYou are given n balls on a 2D grid. ballsi = xi, yi is the position of ball i, and you are also given a non-negative integer d. Two balls are linked when they lie on the same row…
Last asked Jun 2026
+1
All nodes at distance K in a binary treeCodingGiven a binary tree, a target node and k, return every node exactly k edges away from the target. Add parent links (or turn the tree into an undirected graph), then search outward…
Last asked Jun 2026
Pick the root that needs the fewest edge reversalsCodingYou are given a tree with n nodes labeled 1 to n. Its n - 1 edges are directed: each edge (u, v) points from u to v. Ignoring direction, the edges connect all nodes into a tree…
Last asked May 2026
Agent to-do list with task dependenciesCodingBuild the task tracker an AI agent uses to plan its work. The question comes in three parts. Each part builds on the one before, so keep earlier behavior working. A status is an…
Last asked May 2026
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Reconstruct a string from chained segmentsCodingA log-shipping service splits a long message into fragments and sends them out of order. Each fragment is a triple startid, endid, payload: it covers the stretch from marker…
Last asked May 2026
Maximum candies from boxes with keysCodingSome boxes are open and some are locked. Each box holds candies, keys to other boxes, and more boxes. You start with a few boxes. You may open a box once you have it and it is…
Last asked May 2026
Validate a parent-child forestCodingGiven a list of parent-child pairs, decide whether they form a valid forest: no node has two parents, there are no cycles, and every tree has one root. Return the reason when it…
Last asked May 2026
Count connected components in an undirected graphCodingGiven n nodes and a list of undirected edges, return the number of connected components. It was also asked with products: each pair says two products are in the same category, and…
Last asked May 2026
Resolve package versions from dependency constraintsCodingPackages have versions, and each version may require other packages within a version range. Parse the dependency specs, answer queries about which versions satisfy a constraint…
Last asked May 2026
Uniformly random spanning tree over node groupsCodingYou are given groups, a list of K disjoint, non-empty lists of integer node IDs. Nodes inside a group are already connected to each other; different groups are not connected. You…
Last asked May 2026
Referral networkCodingImplement a referral network: users refer other users, and the network records who referred whom. Support adding referrals and answering questions about a user's referrals, such…
Last asked May 2026
Does a word exist as a path in a graph?CodingEvery node of a graph holds a letter. Decide whether a word can be spelled by walking along edges, one letter per node. Agree on whether a node may be used twice, and give the…
Last asked May 2026
Redundant connection: find the extra edgeCodingA tree had one extra edge added, so the undirected graph now has exactly one cycle. Return the edge that can be removed to leave a tree; if several could, return the one that…
Last asked Apr 2026
+1
Island areas and water boundariesCodingYou are given an m x n grid of characters. Each cell is '1' (land) or '0' (water). Land cells that share a side (up, down, left or right) belong to the same island. Diagonal cells…
Last asked Apr 2026
DAG utility with add, validate and queryCodingBuild a small directed-acyclic-graph helper: add edges, reject ones that would create a cycle, and answer reachability or ordering queries over the graph. Reported on…
Last asked Apr 2026
Shortest travel times from a start node to target nodesCodingA weighted graph models a road map. Given a start node and one or more target nodes, return the shortest travel time (an ETA) from the start to each target. Use Dijkstra's…
Last asked Apr 2026
Detonate the most bombs in a chain reactionCodingEach bomb has a position and a blast radius. Setting one off detonates every bomb within its radius, and those set off others in turn. Return the largest number of bombs that can…
Last asked Apr 2026
Best-scoring ski run through a trail mapCodingA ski area has mapped its one-way trails between named checkpoints. The trail map has no cycles: once you ski down a trail you can never get back to where you were. Every trail…
Last asked Mar 2026
Kubernetes service dependency queriesCodingYou get a list of Kubernetes services, each with attributes, a status and the services it depends on. Build a structure over them and answer queries such as which services a…
Last asked Feb 2026
Detect and break cycles in pod dependenciesCodingYou have many pods, and a pod may depend on other pods. 1. Dependencies are directed. Report whether they contain a cycle, much like checking whether a course schedule can be…
Last asked Feb 2026
Decaying power levels across a graphCodingSome nodes of a graph are power sources with a starting level, and power weakens as it travels along edges. Compute the power level that reaches every node (when several sources…
Last asked Feb 2026
Shortest relationship path between two peopleCodingPeople are linked by relationships (a graph where each edge is a direct relationship). Given two people, return the shortest chain of relationships that connects them, or say that…
Last asked Feb 2026
Build, validate and prune a computation graphCodingImplement a small graph of neural-network operations: add nodes and dependencies, check structural rules, detect cycles, and remove branches that do not contribute to the required…
Last asked Feb 2026
Grid path that keeps its highest cell as low as possibleCodingEach cell of an m x n grid holds a height. Find a path from the top-left to the bottom-right cell, moving up, down, left or right, whose highest cell is as low as possible, and…
Last asked Feb 2026
Shortest cycle through each nodeCodingIn a weighted graph, find for every node the cost of the cheapest cycle that passes through it, or report that none exists. Only the title of this report was public; discuss the…
Last asked Feb 2026
Check that a parent array forms a valid treeCodingYou get an array where parenti is the parent of node i (the root has no parent, for example -1). Return whether the array describes one valid tree: exactly one root, no cycles…
Last asked Feb 2026
+1
Cheapest flights within K stopsCodingGiven flights as (from, to, price), a source, a destination and an integer k, return the cheapest price from the source to the destination using at most k stops, or -1 if there is…
Last asked Feb 2026
Design a read-heavy service for org chart subordinate countsSystem designGiven manager-report relationships for a company, answer "how many people are under this person?" for any employee, at high read volume. Then handle changes: when a reporting…
Last asked Feb 2026
Build order for a package and its dependenciesCodinggetdependencies(package) returns a package's direct dependencies; the whole graph is not given up front. Given a target package, return an order in which to build it and…
Last asked Jan 2026
Order feature activations by their dependenciesCodingFeatures must be turned on in an order that respects their dependencies (a feature can only be activated after the features it depends on). Given the features and dependencies…
Last asked Jan 2026
Time for an infection to spread through a binary treeCodingA binary tree catches fire (or an infection) at one given node. Every minute it spreads to the neighbours of each burning node: its children and its parent. Return how many…
Last asked Jan 2026
Group GPUs by node, then partition them by linksCodingGiven a list of GPUs with the node each sits on and the high-speed links between them, group the GPUs by node and then split each group into sets connected through links. Only the…
Last asked Jan 2026
Topological sort of a directed graphCodingReturn an order of a directed graph's nodes in which every edge goes from earlier to later, or report a cycle. Give Kahn's algorithm and the DFS version. Only the title of this…
Last asked Jan 2026
Decide whether two people in a family tree are relatedCodingYou get a family tree as parent and child links. Given two people in it, decide whether they are related through the tree. Agree on what "related" means with the interviewer (for…
Last asked Jan 2026
Distance from every node to the cycleCodingA connected graph contains exactly one cycle. For every node, return its distance to the nearest node on the cycle. Find the cycle by trimming leaves, then run a multi-source BFS…
Last asked Jan 2026
Fastest trip when two travellers may meet and ride togetherCodingTwo people start at different nodes of a graph and both need to reach the same destination. They may travel separately, or meet at some node and take the bus together from there…
Last asked Jan 2026
Redundant connection in a directed graphCodingA rooted tree had one extra directed edge added. Given the edge list, return the edge to remove so the rest is a rooted tree again, taking the last such edge in the input when…
Last asked Jan 2026
Design a package installer with dependenciesSystem designDesign a package installer: a user asks for a package and the installer fetches it together with everything it depends on, in a valid order. Cover how dependencies and versions…
Last asked Jan 2026
Match people to questions using tags and prioritiesCodingPeople have skill tags and questions have tags and priorities. Assign questions to people so each question goes to someone whose tags fit, higher-priority questions are served…
Last asked Dec 2025
Minimum time to finish target courses in a prerequisite DAGCodingCourses form a directed acyclic graph of prerequisites and each course takes a given time; any number of courses can run at once as soon as their prerequisites are done. Return…
Last asked Dec 2025
Making a large islandCodingIn a binary grid you may change at most one water cell to land. Return the size of the largest island you can end up with. Label each island and its size once, then try each water…
Last asked Dec 2025
Course schedule: can every course be finished?CodingGiven a number of courses and prerequisite pairs, return whether it is possible to finish every course, which means the prerequisite graph has no cycle. Use Kahn's algorithm or…
Last asked Dec 2025
Top K similar movies from a similarity graphCodingMovies are nodes with a rating, and an edge links two similar movies; similarity carries across edges. Given a movie and k, return the k highest-rated movies reachable from it…
Last asked Dec 2025
Shortest delivery route that avoids dangerous stopsCodingA delivery network is a graph of stops, and some stops are marked dangerous. Find the shortest route from the depot to the destination that avoids the dangerous stops (or limits…
Last asked Dec 2025
Word ladderCodingGiven a start word, an end word and a word list, find the length of the shortest sequence from start to end in which each step changes exactly one letter and every word after the…
Last asked Dec 2025
Largest group of two-digit numbers that share digitsCodingYou get a list of two-digit numbers. Two numbers are linked when they share a digit, and links carry over (if a shares with b and b with c, all three are in one group). Return the…
Last asked Dec 2025
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Detect a cycle in a directed graphCodingDecide whether a directed graph contains a cycle, using depth-first search with node states or Kahn's topological sort. Variants that came up: start with a linked list (fast and…
Last asked Dec 2025
+1
Best currency conversion rate across exchange quotesCodingYou run a currency desk. You are given a list of quotes (from, to, rate): one unit of from buys rate units of to. A quote works only in the direction given; the reverse is…
Last asked Nov 2025
Products your friends bought that you haven'tCodingA user has a list of friends and a list of purchases; each purchase has a product id, an amount and a purchase id, and a product catalog maps product ids to names. Return the…
Last asked Oct 2025
Find the first error in a log, then trace failures through dependenciesCoding1. A service's log lines are tagged Info, Warn or Error. Once the first Error appears the service is down, so every later line is an Error too, and the line just before the first…
Last asked Sep 2025
Shortest path that avoids blocked nodesCodingGiven an unweighted graph, a start node and a set of blocked nodes that cannot be entered, return the shortest distance from the start to every node (or to a given end node), with…
Last asked Sep 2025
Course schedule: detect a cycle and return an orderCodingCourses have prerequisites. Decide whether all courses can be finished (the prerequisite graph has no cycle), and if so return a valid order to take them. Use depth-first search…
Last asked Sep 2025
Shortest path in an unweighted graph: BFS versus DFSCodingExplain how to find the shortest path between two nodes of an unweighted graph and its time complexity, without necessarily writing code. Then compare: why breadth-first search…
Last asked Sep 2025
Group movies by graph traversalCodingMovies are linked to each other (for example by shared attributes or similarity pairs). Put every movie into its group, where a group is a set of movies connected through links…
Last asked Sep 2025
Recommend accounts your followees followCodingGiven a dictionary from each user to the people they follow, for example {A: B, C, B: C, D, C: E}, return for a user every account followed by the people they follow that they…
Last asked Aug 2025
Reach a destination by bus with limited walkingCodingYou get start and end points on a grid, a walking budget k, and bus routes between pairs of stations, all two-way. Riding a bus costs no walking; walking between points costs…
Last asked Aug 2025
Validate a course catalog's prerequisitesCodingA course catalog lists each course and its prerequisites. Check that the catalog is valid: every prerequisite exists and there is no cycle, so all courses can be taken in some…
Last asked Aug 2025
Fewest new paths to connect every islandCodingYou have N named islands and a list of existing two-way paths between them. Return the fewest new paths needed so every island can reach every other: count the connected…
Last asked Jul 2025
Shipping route cost pathsCodingA parcel carrier publishes its shipping routes as a list of strings. Each string has the form source:target:method:cost: - source and target are country codes. A route ships one…
Minimum starting vertices to reach a cyclic directed graphCodingYou are given a directed graph with n vertices labeled 0 to n - 1 and a list edges, where edgesi = u, v is a directed edge from u to v. The graph may contain cycles, self-loops…
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Largest island perimeter in a gridCodingYou are given an m x n grid where each cell is either land ("1") or water ("0"). Land cells that touch horizontally or vertically (not diagonally) belong to the same island. Treat…
Tallest building between parking lotsCodingA city block is drawn as a rectangular grid of strings. Each tile is one of: - 'P': a parking lot. Its height is fixed at 0. - '-': a lot where a building can go. You choose its…
+1
Root of the largest tree in a forestCodingYou are given a list relations. Each entry child, parent says that parent is the direct parent of child. Together the relations form a forest: there are no cycles, and every node…
Largest group of mutual strangers in an acquaintance forestCodingYou are given n people numbered 0 to n - 1 and a list connections, where each pair a, b means a and b know each other (the relation is symmetric). The acquaintances contain no…
+1
Group duplicate records that share any propertyCodingYou are given a list of records. Each record has a unique integer ID and three properties, for example a name, an email and a phone number: Two records are duplicates when they…
Longest path in a DAG from an edge listCodingYou are given a directed acyclic graph as a list of edges. Each edge is a pair u, v of node names and means there is an edge from u to v. A node exists only if it appears in at…
Connect points that share a row or columnCodingDesign a structure over an unbounded 2D grid. Each cell is either empty or holds a point. You can move from one point to another point in one step when the two points share a row…
Spell a word with letter blocks, one block per letterCodingYou have a set of letter blocks. Each block is a list of lowercase characters printed on its faces. You also get a target string. Implement canform(blocks: listliststr, target:…
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Find bottleneck dependencies in a parallel buildCodingYou are given n build targets numbered 0 to n - 1 and a list of directed edges edges. An edge u, v means target v cannot start building until target u has finished. The graph has…