dartterm/lib/algorithms/kruskal.dart
2023-09-21 19:29:34 -07:00

34 lines
844 B
Dart

import 'package:dartterm/algorithms/union_find.dart';
class Edge<T> {
final int src, dst;
final T value;
final double score; // higher score is better
const Edge(this.src, this.dst, this.value, this.score);
}
List<Edge<T>> kruskal<T>(int nRegions, List<Edge<T>> srcEdges) {
var edges = List.from(srcEdges); // copy so we can mutate it
edges.sort((e0, e1) => -e0.score.compareTo(e1.score));
List<Edge<T>> spanningEdges = [];
var connected = UnionFind(nRegions);
for (var i = 0; i < edges.length; i++) {
var edge = edges[i];
if (connected.find(edge.src) == connected.find(edge.dst)) {
continue;
}
spanningEdges.add(edge);
connected.union(edge.src, edge.dst);
// break early if we run out of regions
nRegions -= 1;
if (nRegions == 1) {
break;
}
}
return spanningEdges;
}