refactor: remove duplicated adjacency map building, use GraphUtils

code_cleanup: GraphIsomorphismAnalyzer had a private buildAdjacencyMap()
method identical to GraphUtils.buildAdjacencyMap() — removed it and
switched to the shared utility. MotifAnalyzer had an inline 8-line
neighbor cache loop identical to GraphUtils — replaced with one-liner.

Both changes reduce duplication and ensure consistent null-safety
handling (GraphUtils checks for null neighbors). All 1009 tests pass
(2 pre-existing InfluenceSpreadSimulator failures unchanged).

Author: sauravbhattacharya001

Gvisual/src/gvisual/GraphIsomorphismAnalyzer.java

@@ -150,8 +150,8 @@ public IsomorphismResult analyze() {
         }
 
         // Build adjacency sets for fast lookup
-        Map<String, Set<String>> adj1 = buildAdjacencyMap(graph1);
-        Map<String, Set<String>> adj2 = buildAdjacencyMap(graph2);
+        Map<String, Set<String>> adj1 = GraphUtils.buildAdjacencyMap(graph1);
+        Map<String, Set<String>> adj2 = GraphUtils.buildAdjacencyMap(graph2);
 
         // Group vertices by degree for pruning
         Map<Integer, List<String>> byDegree1 = groupByDegree(graph1, vertices1);
@@ -209,14 +209,6 @@ private List<Integer> getSortedDegreeSequence(Graph<String, edge> g,
     /**
      * Build adjacency map: vertex → set of neighbors.
      */
-    private Map<String, Set<String>> buildAdjacencyMap(Graph<String, edge> g) {
-        Map<String, Set<String>> adj = new HashMap<String, Set<String>>();
-        for (String v : g.getVertices()) {
-            adj.put(v, new HashSet<String>(g.getNeighbors(v)));
-        }
-        return adj;
-    }
-
     /**
      * Group vertices by their degree.
      */

Gvisual/src/gvisual/MotifAnalyzer.java

@@ -90,15 +90,7 @@ public MotifAnalyzer compute() {
         }
 
         // Build neighbor cache for O(1) lookups
-        neighborCache = new HashMap<String, Set<String>>(vertices.size() * 2);
-        for (String v : vertices) {
-            Collection<String> neighbors = graph.getNeighbors(v);
-            Set<String> set = new HashSet<String>();
-            if (neighbors != null) {
-                set.addAll(neighbors);
-            }
-            neighborCache.put(v, set);
-        }
+        neighborCache = GraphUtils.buildAdjacencyMap(graph);
 
         // Initialize participation counts
         for (String v : vertices) {