| 1 | union-find optimizationGoogle DeepMind 1Coding problem with O(n^3) brute force, optimized to O(n^2), where the optimal solution uses Union-Find; asked to implement brute force firs… | cp-algorithms: Disjoint Set UnionLeetCode set: graphs, union-find and Dijkstra (684, 547, 269, 1514, 141)Union-find with path compression; LC 684 |
| 1 | anagram string problemsUnspecified frontier 1Two string-processing / anagram-style coding problems at medium-hard level (e.g. LeetCode "Count Anagrams") | LeetCode set: arrays, hashing and two pointers (271, 238, 217, 49, 438, 1570, 15)LC 438 and 49 anagram counting |
| 1 | tree diameter in nodesMeta (org unspecified) 1Coding: variation of LeetCode 543 (Diameter of Binary Tree) counting nodes instead of edges | LeetCode set: trees (543, 297, 426, 429)LC 543 diameter, count nodes not edges |
| 1 | longest valid parenthesesMeta (org unspecified) 1Coding: LeetCode 32 (Longest Valid Parentheses) | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)LC 32 longest valid parentheses |
| 1 | sparse vector dot productMeta (org unspecified) 1Online screen: sparse vector dot product; after a hashmap solution, asked for another solution without hashing (two pointers) | LeetCode set: arrays, hashing and two pointers (271, 238, 217, 49, 438, 1570, 15)LC 1570 sparse dot product, two-pointer over index lists |
| 1 | 2D sliding window maxOpenAI 1Largest Local Values in a Matrix generalized to a k x k window instead of 3 x 3 (aim for O(n^2), e.g. two 1-D sliding-window maxima) | LeetCode set: sliding window and prefix sums (76, 239, 2373, 1413)LC 2373 generalized with monotonic deques (LC 239) |
| 1 | grid DP with jumpsOpenAI 1Grid board N x M, start at (0, p); move to (i+1, j-1), (i+1, j), (i+1, j+1) or a special jump (i+2, j) used at most K times; find max score … | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)OpenAI Interview Notes (unofficial reconstructed problems)LC 931 falling path; grid-path-limited-jumps |
| 1 | subset max separationAnthropic 1Given an N x M matrix A of impact points (launches x teams), choose a subset of launches to maximize the max over teams i of sum_j |score[j]… | The Algorithm Design Manual, 3rd EditionCompetitive Programmer's HandbookBitmask/backtracking subset search modelling |
| 1 | threshold infection simulationAnthropic 1Simulate infection spread on a 2D grid where a cell becomes infected once K neighbors are infected; optimize beyond O(NM) per step using BFS | OpenAI Interview Notes (unofficial reconstructed problems)infection-spread K-neighbour threshold |
| 1 | LeetCode mediumAnthropic 1Anthropic Fellows live technical (60 min): a single LeetCode-medium problem | NeetCode 150 (practice list)Single LeetCode medium practice |
| 1 | GPU node grouping union-findxAI 1GPU node grouping with union-find | cp-algorithms: Disjoint Set UnionUnion-find grouping of GPU nodes |
| 1 | follow links find endpoint or loopOpenAI 1New grad CoderPad OA Q1 "Simple Network": each node links to at most one next node; from start_node_id follow from_ids/to_ids links and retu… | LeetCode set: graphs, union-find and Dijkstra (684, 547, 269, 1514, 141)LC 141 cycle detection on next-pointer graph |
| 1 | count paths through 4 shop typesOpenAI 1New grad CoderPad OA Q2 "Count Paths": given shop types 0–3 and roads between shops, count the paths that visit one shop of each of the 4 ty… | Algorithms (free textbook)MIT 6.006 Introduction to Algorithms (Spring 2020, OCW)DP over DAG paths through ordered shop types |
| 1 | grid spread simulationOpenAI 1 · 1 staff+Disease Spread in Flower Grid. | OpenAI Interview Notes (unofficial reconstructed problems)LeetCode set: grid BFS and state-space search (200, 1905, 994, 1091, 490, 864, 1293)Grid spread simulation; BFS by day |
| 1 | LRU cache with TTLOpenAI 1, xAI 1Implement an LRU cache with O(1) get/put, then add TTL. | LeetCode set: design problems (146, 341, 1146, 2502, 2408)LC 146 LRU, then lazy TTL expiry |
| 1 | first n Fibonacci numbersOpenAI 1Write a Python function that displays the first n Fibonacci numbers. | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)LC 509 Fibonacci iteratively |
| 1 | streaming top-k frequentGoogle DeepMind 1You are receiving an unbounded stream of event IDs. Return the k most frequent IDs seen so far, at any point, with bounded memory. | LeetCode set: heaps and top-k (347, 973, 253)Heap plus hash map for streaming top-k |
| 1 | closest key dictionary lettersGoogle DeepMind 1Closest key: given a dictionary with letter keys and lists of letters as values, find the closest key. | LeetCode set: graphs, union-find and Dijkstra (684, 547, 269, 1514, 141)Graph Theory playlistBFS over adjacency dictionary |
| 1 | product of array except selfMeta MSL 1Given an array nums of n integers where n > 1, return an output array (product of array except self). | LeetCode set: arrays, hashing and two pointers (271, 238, 217, 49, 438, 1570, 15)LC 238 prefix/suffix products |
| 1 | minimum window substringMeta MSL 1Find the minimum window in S which will contain all the characters in T. | LeetCode set: sliding window and prefix sums (76, 239, 2373, 1413)LC 76 minimum window substring |
| 1 | serialize deserialize binary treeMeta MSL 1Serialize and deserialize a binary tree. | LeetCode set: trees (543, 297, 426, 429)LC 297 serialize/deserialize |
| 1 | binary tree to doubly linked listMeta MSL 1Convert a binary tree to a circular doubly linked list. | LeetCode set: trees (543, 297, 426, 429)LC 426 tree to circular doubly linked list |
| 1 | alien dictionaryMeta MSL 1Alien dictionary: determine character ordering from a sorted word list. | LeetCode set: graphs, union-find and Dijkstra (684, 547, 269, 1514, 141)LC 269 topological sort of letters |
| 1 | k closest/top-k/meeting roomsMeta MSL 1K closest points to origin; top-k frequent elements; minimum number of conference rooms. | LeetCode set: heaps and top-k (347, 973, 253)LC 973, 347, 253 |
| 1 | regex matchingMeta MSL 1Regular expression matching with '.' and '*'. | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)LC 10 regex DP |
| 1 | streaming top-k engaged itemsMeta MSL 1Two-part warm-up: given a stream of user actions, return the k most engaged-with items. Then: why might your heap solution be the wrong choi… | LeetCode set: heaps and top-k (347, 973, 253)Streaming top-k; bounded-memory follow-up |
| 1 | nested list iteratorxAI 1Write an iterator class that lazily flattens an arbitrarily nested list of lists/integers: no generators, explicit state. | LeetCode set: design problems (146, 341, 1146, 2502, 2408)LC 341 lazy nested iterator |
| 1 | from-scratch data structuresAnthropic 1Coding round: after solving a problem cleanly with the standard library, implement the data structures from scratch and defend your complexi… | Algorithms, 4th Edition (booksite)Elements of Programming Interviews in PythonImplement heap, hash table, union-find from scratch |
| 1 | snapshot arrayxAI 1Snapshot Array | LeetCode set: design problems (146, 341, 1146, 2502, 2408)LC 1146 snapshot array |
| 1 | hierarchical binary search versionsOpenAI 1Find the latest Python version that supports a given package (binary search, extended to hierarchical binary search). | OpenAI Interview Notes (unofficial reconstructed problems)LeetCode set: binary search on answers (374, 278)version-dependency hierarchical binary search |
| 1 | text justificationAnthropic 1Implement a function to justify a list of words within a given width. | LeetCode set: simulation and parsing (68, 227, 1041)LC 68 text justification |
| 1 | memory allocator intervalsOpenAI 1Memory Allocator (75 min) | LeetCode set: design problems (146, 341, 1146, 2502, 2408)OpenAI Interview Notes (unofficial reconstructed problems)LC 2502; memory-allocator intervals |
| 1 | top-k frequent events streamGoogle DeepMind 1Most Frequent Events in a Stream (3 parts / 45 min) | LeetCode set: heaps and top-k (347, 973, 253)Top-k frequent events in a stream |
| 1 | array scan graph DFS warmupGoogle DeepMind 1Warm-Up: Scanning an Array and Traversing a Graph Depth-First (3 parts / 30–45 min) | NeetCode Roadmap (with video explanations)Graph Theory playlistArray scan then graph DFS warm-ups |
| 1 | BFS locked doors keysGoogle DeepMind 1Shortest Paths Through Locked Doors (3 parts / 45–60 min) | LeetCode set: grid BFS and state-space search (200, 1905, 994, 1091, 490, 864, 1293)LC 864 BFS with key bitmask state |
| 1 | token game winning positionsGoogle DeepMind 1Winning Positions in a Token-Moving Game (3 parts / 45–60 min) | cp-algorithms: Games on arbitrary graphs (and Sprague-Grundy)Retrograde win/lose labelling on game graph |
| 1 | BFS maze path printingMeta MSL 1Maze Solver with Path Printing | LeetCode set: grid BFS and state-space search (200, 1905, 994, 1091, 490, 864, 1293)Introduction to the A* AlgorithmLC 1091 BFS with came_from path printing |
| 1 | max unique chars word subsetMeta MSL 1Maximize Unique Characters from Word List | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)LC 1239 backtracking with bitmasks |
| 1 | three cards sum 15Meta MSL 1Card Game: Find Three Cards Summing to 15 | LeetCode set: arrays, hashing and two pointers (271, 238, 217, 49, 438, 1570, 15)LC 15 3Sum pattern for sum-15 |
| 1 | BFS maze directional gatesMeta MSL 1Maze Pathfinding Algorithm | LeetCode set: grid BFS and state-space search (200, 1905, 994, 1091, 490, 864, 1293)Introduction to the A* AlgorithmLC 490 maze with directional moves |
| 1 | SQL executor meeting roomsOpenAI 1Design SQL / Meeting Rooms: build a SQL query executor or solve the meeting rooms scheduling problem. | LeetCode set: design problems (146, 341, 1146, 2502, 2408)LeetCode set: heaps and top-k (347, 973, 253)LC 2408 SQL; LC 253 meeting rooms |
| 1 | n-ary treeOpenAI 1N- ary tree | LeetCode set: trees (543, 297, 426, 429)LC 429 N-ary traversal |
| 1 | GPU capacity switching limitsMistral 1Compute Remaining GPUs With Switching Limits: n GPU clusters with fixed daily capacities capacity[i]; each day starts fresh with full capaci… | LeetCode set: dynamic programming (300, 188, 931, 32, 10, 509, 1239, 688)LC 188-style K-switch capacity DP |
| 1 | expression parser + and *Mistral 1Implement a parser to compute the mathematical result of a string containing numbers and basic operators like + and * (without parentheses). | LeetCode set: simulation and parsing (68, 227, 1041)LC 227 stack-based + and * evaluation |
| 1 | lookups and deduplicationMistral 1Solve a series of progressive coding challenges focused on efficient lookups and deduplication using arrays and sets. | LeetCode set: arrays, hashing and two pointers (271, 238, 217, 49, 438, 1570, 15)NeetCode Roadmap (with video explanations)Hash-set lookups and dedup patterns |