PRIMS MST added

Author: Subham1999

.idea/workspace.xml

@@ -16,6 +16,10 @@ public static <V> Edge<V, V> createSimpleEdgeUnWeighted(V v1, V v2) {
     return new Edge<>(Vertex.create(v1), Vertex.create(v2), 0D);
   }
 
+  public static <V> Edge<V, V> createEdge(V v1, V v2, double weight) {
+    return new Edge<>(Vertex.create(v1), Vertex.create(v2), weight);
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;
@@ -29,4 +33,9 @@ public boolean equals(Object o) {
   public int hashCode() {
     return Objects.hash(getVertex1(), getVertex2(), getWeight());
   }
+
+  @Override
+  public String toString() {
+    return "<" + vertex1.getKey() + "--" + vertex2.getKey() + "|" + weight + '>';
+  }
 }

src/main/java/com/thealgorithm/graph/Edge.java

@@ -32,4 +32,10 @@ public void addEdge(Edge<K, V> edge) {
       }
     }
   }
+
+  void clear() {
+    vertexSet.clear();
+    edgeSet.clear();
+    isDirected = false;
+  }
 }

src/main/java/com/thealgorithm/graph/Graph.java

@@ -0,0 +1,44 @@
+package com.thealgorithm.graph;
+
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.PriorityQueue;
+import java.util.Set;
+
+/**
+ * @author: Subham Santra
+ */
+public class PrimsMinimumSpanningTree {
+
+  public <K, V> Set<Edge<K, V>> findMST(final Graph<K, V> graph) {
+    Set<Vertex<K, V>> visited = new HashSet<>();
+    PriorityQueue<Edge<K, V>> edgePQ =
+        new PriorityQueue<>(Comparator.comparingDouble(Edge::getWeight));
+    Set<Edge<K, V>> minimumSpanningTree = new HashSet<>();
+
+    edgePQ.addAll(graph.getEdgeSet());
+
+    while ((!edgePQ.isEmpty()) && (visited.size() < graph.getVertexSet().size())) {
+      Edge<K, V> currentMinimumEdge = edgePQ.poll();
+      visited.add(currentMinimumEdge.getVertex1());
+      visited.add(currentMinimumEdge.getVertex2());
+      minimumSpanningTree.add(currentMinimumEdge);
+    }
+
+    return minimumSpanningTree;
+  }
+
+  // Test code
+  public static void main(String[] args) {
+    Graph<Integer, Integer> graph = new Graph<>(false);
+
+    graph.addEdge(Edge.createEdge(1, 2, 4));
+    graph.addEdge(Edge.createEdge(1, 3, 1));
+    graph.addEdge(Edge.createEdge(1, 5, 3));
+    graph.addEdge(Edge.createEdge(5, 4, 1));
+    graph.addEdge(Edge.createEdge(5, 3, 1));
+    graph.addEdge(Edge.createEdge(2, 4, 2));
+
+    System.out.println(new PrimsMinimumSpanningTree().findMST(graph));
+  }
+}

src/main/java/com/thealgorithm/graph/PrimsMST.java

@@ -105,7 +105,9 @@ ParkingSpot parkThis(Vehicle vehicle) {
 class ParkingLot {
   List<Level> parkingLevels;
 
-  void park(Vehicle vehicle) {}
+  void park(final Vehicle vehicle) {
+
+  }
 }
 
 public class ParkingLotLLD {}