Overview
Maximum Cardinality Search is a graph algorithm that extracts graph structure such as components, rankings, closures, flows, or matchings. It helps expose graph structure that is hard to see from local edges alone.
CoreSource checked
Maximum Cardinality Search
Maximum Cardinality Search extracts structure such as components, tours, rankings, or closures from a graph.
Quick Facts
Compact metadata for implementation and discovery.
- Category
- Graph Traversal
- Difficulty
- Intermediate
- Family
- Graph Algorithm
- Tier
- Core
- Status
- Verified
- Review
- Source Checked
- Sources
- 2
- Formulas
- 0
- Relationships
- 2
- Code example
- Ready
- Visualization
- Ready
Core Concepts
graph structurefrontier or residual stateconnectivityvisited stateedge traversal
Quick facts
Complexity
Runtime and memory behavior at a glance.
Best
O(V + E)
Average
O(V + E)
Worst
O(V + E)
Space
O(V)
When to Use
- Use Maximum Cardinality Search when the graph question matches its traversal, ranking, flow, or matching model.
- Use it when exact graph structure is more valuable than an approximate summary.
When Not to Use
- Avoid when graph direction, weights, or capacities do not match the method.
- Avoid when approximate graph summaries are enough and exact traversal is too expensive.
What It Does
- Explores graph relationships
- Maintains frontier, component, or residual state
- Returns structural information about the graph
Use Cases
- Network analysis
- Dependency analysis
- Graph optimization
Inputs
- Graph
- Start nodes or selected subgraph
- Weights or capacities if needed
Outputs
- Visited order
- Graph structure
- Flow, component, ranking, or matching result
Pseudocode
- 1.Initialize graph state, scores, components, or residual capacity
- 2.Visit or update eligible nodes and edges
- 3.Apply the method's traversal, ranking, matching, or flow rule
- 4.Repeat until no useful updates remain
- 5.Return the graph structure or score result
Canonical Example
- Input
- graph = small directed graph
- Output
- visited order, component, ranking, flow, or matching result
- Explanation
- Maximum Cardinality Search updates graph state until the requested structural result is available.
Implementation Notes
- Represent edge direction, weights, and capacities explicitly.
- Keep traversal state local so repeated runs do not leak state.
Common Pitfalls
- Treating directed and undirected edges the same changes the result.
- Not resetting visited, residual, or component state corrupts later traversals.
Interactive Mechanism Walkthrough
Graph Frontier & Edge RelaxationShow graph nodes and edges changing color as the traversal, ranking, or flow state evolves.
Step 1 of 5: Initialize graph state, scores, components, or residual capacity
graphNotes
Maximum Cardinality Search operates in O(V + E) time and O(V) space within the Graph Algorithm family. Often compared with Breadth-First Search and Depth-First Search.
Sources (2)
What each reference supports for this entry.
Introduction to Algorithms (CLRS)
BookTextbook support for Maximum Cardinality Search's standard algorithm design, invariants, and complexity analysis.
Open sourceThe Algorithm Design Manual
BookAlgorithm catalog support for Maximum Cardinality Search's problem context, known alternatives, and practical selection tradeoffs.
Open sourceExplore Next
Good next jumps from the relationship graph, ranked for useful discovery.
Relationships
View full relationship pageConceptual neighborBreadth-First Search
Maximum Cardinality Search and Breadth-First Search address nearby graph traversal problems but make different implementation tradeoffs.
Related Algorithms
Tags
Graph