src/algorithms/graph/kruskal/kruskal.js

@@ -7,53 +7,31 @@ import DisjointSet from '../../../data-structures/disjoint-set/DisjointSet';
  * @return {Graph}
  */
 export default function kruskal(graph) {
-  // It should fire error if graph is directed since the algorithm works only
-  // for undirected graphs.
+  // Check for directed graph
   if (graph.isDirected) {
-    throw new Error('Kruskal\'s algorithms works only for undirected graphs');
+    throw new Error("Kruskal's algorithm works only for undirected graphs");
   }
 
-  // Init new graph that will contain minimum spanning tree of original graph.
+  // Initialize the MST graph
   const minimumSpanningTree = new Graph();
 
-  // Sort all graph edges in increasing order.
-  const sortingCallbacks = {
+  // Sort all edges by weight in ascending order
+  const sortedEdges = new QuickSort({
     /**
      * @param {GraphEdge} graphEdgeA
      * @param {GraphEdge} graphEdgeB
      */
-    compareCallback: (graphEdgeA, graphEdgeB) => {
-      if (graphEdgeA.weight === graphEdgeB.weight) {
-        return 1;
-      }
+    compareCallback: (graphEdgeA, graphEdgeB) => graphEdgeA.weight - graphEdgeB.weight,
+  }).sort(graph.getAllEdges());
 
-      return graphEdgeA.weight <= graphEdgeB.weight ? -1 : 1;
-    },
-  };
-  const sortedEdges = new QuickSort(sortingCallbacks).sort(graph.getAllEdges());
+  // Initialize disjoint sets for vertices
+  const disjointSet = new DisjointSet((vertex) => vertex.getKey());
+  graph.getAllVertices().forEach((vertex) => disjointSet.makeSet(vertex));
 
-  // Create disjoint sets for all graph vertices.
-  const keyCallback = (graphVertex) => graphVertex.getKey();
-  const disjointSet = new DisjointSet(keyCallback);
-
-  graph.getAllVertices().forEach((graphVertex) => {
-    disjointSet.makeSet(graphVertex);
-  });
-
-  // Go through all edges started from the minimum one and try to add them
-  // to minimum spanning tree. The criteria of adding the edge would be whether
-  // it is forms the cycle or not (if it connects two vertices from one disjoint
-  // set or not).
-  for (let edgeIndex = 0; edgeIndex < sortedEdges.length; edgeIndex += 1) {
-    /** @var {GraphEdge} currentEdge */
-    const currentEdge = sortedEdges[edgeIndex];
-
-    // Check if edge forms the cycle. If it does then skip it.
+  // Add edges to the MST if they don’t form a cycle
+  for (const currentEdge of sortedEdges) {
     if (!disjointSet.inSameSet(currentEdge.startVertex, currentEdge.endVertex)) {
-      // Unite two subsets into one.
       disjointSet.union(currentEdge.startVertex, currentEdge.endVertex);
-
-      // Add this edge to spanning tree.
       minimumSpanningTree.addEdge(currentEdge);
     }
   }