Add stop condition to Boruvkas algorithm

Author: williamfiset

src/main/java/com/williamfiset/algorithms/graphtheory/Boruvkas.java

@@ -71,6 +71,7 @@ private void solve() {
     UnionFind uf = new UnionFind(n);
 
     while (uf.components > 1) {
+      boolean stop = true;
       Edge[] cheapest = new Edge[n];
 
       // Find the cheapest edge for each component
@@ -81,12 +82,16 @@ private void solve() {
 
         if (cheapest[root1] == null || e.cost < cheapest[root1].cost) {
           cheapest[root1] = e;
+          stop = false;
         }
         if (cheapest[root2] == null || e.cost < cheapest[root2].cost) {
           cheapest[root2] = e;
+          stop = false;
         }
       }
 
+      if (stop) break;
+
       // Add the cheapest edges to the MST
       for (int i = 0; i < n; i++) {
         Edge e = cheapest[i];