union find

Longest Consecutive Sequence

Find the length of the longest consecutive elements sequence in an unsorted array using array scanning and hash lookup.

Surrounded Regions

Transform the matrix in-place by marking regions surrounded by 'X' as 'X', while keeping border-adjacent 'O's intact.

Number of Islands

Count the number of distinct islands in a binary grid using array traversal combined with depth-first search exploration…

Evaluate Division

Compute the results of division queries from given equations using graph traversal and depth-first search efficiently.

Number of Provinces

Solve Number of Provinces by scanning the adjacency matrix and launching DFS once per unvisited city component.

Redundant Connection

Identify and remove the redundant edge that causes a cycle in a graph starting as a tree.

Redundant Connection II

Find and remove the redundant connection in a directed graph that was originally a rooted tree.

Max Area of Island

Find the largest connected land area in a binary grid using array traversal and depth-first search efficiently.

Accounts Merge

Merge accounts by connecting emails and returning each user's sorted email list using array scanning and hash lookup eff…

Couples Holding Hands

This problem requires arranging couples sitting apart in a row with the minimum number of swaps using graph traversal an…

Swim in Rising Water

Solve the problem of swimming through a grid of rising water with a binary search on the valid answer space.

Is Graph Bipartite?

Determine whether an undirected graph can be split into two independent sets using DFS, BFS, or Union Find patterns.

Bricks Falling When Hit

Bricks Falling When Hit challenges your ability to simulate brick falls after sequential erasures using Union Find.

Making A Large Island

Calculate the largest island size by converting at most one zero in a binary grid using array and DFS techniques efficie…

Similar String Groups

Determine the number of connected groups of similar strings by swapping at most two letters using array scanning and has…

Possible Bipartition

Determine if a group of n people with mutual dislikes can be split into two non-conflicting groups using graph traversal…

Minimize Malware Spread

Identify which single infected node to remove to minimize total malware spread in a connected network graph efficiently.

Minimize Malware Spread II

Minimize Malware Spread II asks to minimize the spread of malware in a network of nodes by removing one infected node.

Most Stones Removed with Same Row or Column

Maximize the number of stones removed from a 2D plane using graph traversal and DFS.

Largest Component Size by Common Factor

Find the largest connected component in an array where edges exist between numbers sharing a common factor greater than …

Regions Cut By Slashes

Determine the number of regions in a grid divided by slashes using array scanning and union-find techniques efficiently.

Satisfiability of Equality Equations

Determine if it's possible to assign values to variables such that all equations are satisfied based on equality and ine…

Number of Enclaves

This problem involves finding the number of land cells that cannot reach the boundary in a grid using DFS and array mani…

Lexicographically Smallest Equivalent String

Determine the lexicographically smallest string by modeling character equivalences with union find efficiently.