Allow finding hamiltonian circuits

benches/hamiltonian.rs

@@ -0,0 +1,31 @@
+#![feature(test)]
+
+extern crate petgraph;
+extern crate test;
+
+use petgraph::prelude::*;
+use std::cmp::{max, min};
+use test::Bencher;
+
+use petgraph::algo::hamiltonian_circuits_directed;
+
+#[bench]
+fn hamiltonian_circuits_directed_bench(bench: &mut Bencher) {
+    static NODE_COUNT: usize = 10;
+    let mut g = Graph::new();
+    let nodes: Vec<NodeIndex<_>> = (0..NODE_COUNT).into_iter().map(|i| g.add_node(i)).collect();
+    for i in 0..NODE_COUNT {
+        let n1 = nodes[i];
+        let neighbour_count = i % 8 + 3;
+        let j_from = max(0, i as i32 - neighbour_count as i32 / 2) as usize;
+        let j_to = min(NODE_COUNT, j_from + neighbour_count);
+        for j in j_from..j_to {
+            let n2 = nodes[j];
+            g.add_edge(n1, n2, ());
+        }
+    }
+
+    bench.iter(|| {
+        let _circuit = hamiltonian_circuits_directed(&g).next();
+    });
+}