Updated PrismAlgorithm-IV

Author: shubham9345

src/main/java/com/thealgorithms/graph/PrimAlgorithm.java

@@ -1,8 +1,8 @@
 package com.thealgorithms.graph;
 
-import java.util.ArrayList;
-import java.util.Comparator;
+import java.util.List;
 import java.util.PriorityQueue;
+import java.util.Comparator;
 
 /**
  * This class provides a method to compute the weight of the
@@ -20,24 +20,23 @@ private PrimAlgorithm() {
      * @param node   the target node connected by the edge
      * @param weight the weight of the edge
      */
-    private record Pair(int node, int weight) {
-    }
+    private record Pair(int node, int weight) {}
 
     /**
      * Computes the total weight of the Minimum Spanning Tree (MST)
      * for a given undirected, weighted graph.
      *
      * @param vertices number of vertices in the graph
-     * @param adj      adjacency list representation of the graph
-     *                 for each node, the adjacency list contains a list of
-     *                 {adjacentNode, edgeWeight}
+     * @param adj adjacency list representation of the graph
+     *            for each node, the adjacency list contains a list of
+     *            {adjacentNode, edgeWeight}
      * @return the sum of the edge weights in the MST
      *
      * <p>Time Complexity: O(E log V), where E is the number of edges
      * and V is the number of vertices.</p>
      * <p>Space Complexity: O(V + E) due to adjacency list and visited array.</p>
      */
-    public static int spanningTree(int vertices, ArrayList<ArrayList<ArrayList<Integer>>> adj) {
+    public static int spanningTree(int vertices, List<? extends List<? extends List<Integer>>> adj) {
         // Min-heap to pick edge with the smallest weight
         PriorityQueue<Pair> pq = new PriorityQueue<>(Comparator.comparingInt(Pair::weight));
 
@@ -65,10 +64,11 @@ public static int spanningTree(int vertices, ArrayList<ArrayList<ArrayList<Integ
             mstWeightSum += weight;
 
             // Traverse all adjacent edges
-            for (ArrayList<Integer> edge : adj.get(node)) {
+            for (List<Integer> edge : adj.get(node)) {
                 int adjNode = edge.get(0);
                 int edgeWeight = edge.get(1);
 
+                // Only consider unvisited nodes
                 if (!visited[adjNode]) {
                     pq.add(new Pair(adjNode, edgeWeight));
                 }