+1Number of islands as land is addedCodingA grid starts as all water. Positions are turned into land one at a time; after each addition, return the current number of islands (land cells connected up, down, left or right)…
Last asked Oct 2026
#union-find
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Rank transform of a matrix with distinct valuesCodingGiven an m x n matrix of distinct integers, replace each value with a rank starting at 1 so that in any row or column a larger value gets a larger rank, and ranks are as small as…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
- +4Number of islandsCodingGiven a binary matrix, return how many islands it has: groups of 1 cells connected up, down, left or right (diagonals don't connect).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
+1Earliest 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
Link object tracks across two perception systemsCodingTwo perception systems, A and B, track the same objects around a vehicle independently, each with its own IDs, and each emits observations of its tracks over time. Implement an…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
- 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
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- 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
- 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
Group 3D points within a distance thresholdCodingGiven points in 3D and a distance threshold, group them so that two points closer than the threshold end up in the same group, directly or through a chain of close points. Return…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- Count islands with diagonal connectivityCodingCount the islands in a grid of land and water where land cells are joined in all eight directions, diagonals included.Last asked Apr 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
- Manager and peer relationships with is_manager queriesCodingImplement three functions: - manager(a, b): a is the manager of b. - peer(a, b): a and b have the same manager. - ismanager(a, b): return whether a is a manager of b. Decide how…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
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
Link similar user records by weighted field matchesCodingA data-quality team wants to find user profiles that probably belong to the same person. You get records, a 2D list of strings. The first row is a header of field names, and one…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
- 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
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- +1Largest 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…
- +1Group 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…
- 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…