d803bfe2b1
git-subtree-dir: vendor/ruvector git-subtree-split: b64c21726f2bb37286d9ee36a7869fef60cc6900
98 lines
2.8 KiB
Rust
98 lines
2.8 KiB
Rust
//! Demonstration of graph sparsification for approximate minimum cuts
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use ruvector_mincut::graph::DynamicGraph;
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use ruvector_mincut::sparsify::{karger_sparsify, NagamochiIbaraki, SparseGraph, SparsifyConfig};
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use std::sync::Arc;
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fn main() {
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println!("=== Graph Sparsification Demo ===\n");
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// Create a sample graph (complete graph on 10 vertices)
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println!("Creating complete graph with 10 vertices...");
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let graph = create_complete_graph(10);
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println!(
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"Original graph: {} vertices, {} edges\n",
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graph.num_vertices(),
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graph.num_edges()
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);
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// Demo 1: Benczúr-Karger sparsification
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println!("--- Benczúr-Karger Sparsification ---");
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demo_benczur_karger(&graph);
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// Demo 2: Karger sparsification (convenience function)
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println!("\n--- Karger Sparsification (convenience) ---");
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demo_karger(&graph);
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// Demo 3: Nagamochi-Ibaraki deterministic sparsification
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println!("\n--- Nagamochi-Ibaraki Deterministic Sparsification ---");
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demo_nagamochi_ibaraki(&graph);
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println!("\n=== Demo Complete ===");
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}
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fn create_complete_graph(n: usize) -> DynamicGraph {
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let g = DynamicGraph::new();
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for i in 0..n {
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for j in (i + 1)..n {
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g.insert_edge(i as u64, j as u64, 1.0).unwrap();
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}
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}
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g
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}
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fn demo_benczur_karger(graph: &DynamicGraph) {
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let epsilons = vec![0.1, 0.2, 0.5];
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for epsilon in epsilons {
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let config = SparsifyConfig::new(epsilon).unwrap().with_seed(42);
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let sparse = SparseGraph::from_graph(graph, config).unwrap();
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println!(
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" ε = {:.2}: {} edges ({:.1}% of original)",
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epsilon,
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sparse.num_edges(),
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sparse.sparsification_ratio() * 100.0
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);
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let approx_cut = sparse.approximate_min_cut();
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println!(" Approximate min cut: {:.2}", approx_cut);
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}
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}
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fn demo_karger(graph: &DynamicGraph) {
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let epsilon = 0.15;
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let sparse = karger_sparsify(graph, epsilon, Some(123)).unwrap();
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println!(
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" ε = {:.2}: {} edges ({:.1}% of original)",
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epsilon,
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sparse.num_edges(),
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sparse.sparsification_ratio() * 100.0
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);
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}
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fn demo_nagamochi_ibaraki(graph: &DynamicGraph) {
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let ni = NagamochiIbaraki::new(Arc::new(graph.clone()));
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let k_values = vec![2, 3, 5];
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for k in k_values {
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match ni.sparse_k_certificate(k) {
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Ok(sparse) => {
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let ratio = sparse.num_edges() as f64 / graph.num_edges() as f64;
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println!(
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" k = {}: {} edges ({:.1}% of original)",
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k,
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sparse.num_edges(),
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ratio * 100.0
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);
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}
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Err(e) => {
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println!(" k = {}: Error - {}", k, e);
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}
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}
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}
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}
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