34 lines
844 B
Dart
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;
|
||
|
|
}
|