Basic optimizations for UndirectedSparseGraph

DataStructures/Graphs/UndirectedSparseGraph.cs

@@ -236,19 +236,16 @@ public virtual bool RemoveVertex(T vertex)
             if (!_adjacencyList.ContainsKey(vertex))
                 return false;
 
-            _adjacencyList.Remove(vertex);
-
-            foreach (var adjacent in _adjacencyList)
+            var neighbors = Neighbours(vertex);
+            foreach (var neighbor in neighbors)
             {
-                if (adjacent.Value.Contains(vertex))
-                {
-                    adjacent.Value.Remove(vertex);
-
-                    // Decrement the edges count.
-                    --_edgesCount;
-                }
+                _adjacencyList[neighbor].Remove(vertex);
             }
 
+            _edgesCount -= neighbors.Count;
+
+            _adjacencyList.Remove(vertex);
+
             return true;
         }
 

DataStructures/Lists/DLinkedList.cs

@@ -557,14 +557,7 @@ public virtual void Clear()
         /// <returns>True if found; false otherwise.</returns>
         public virtual bool Contains(T dataItem)
         {
-            try
-            {
-                return Find(dataItem).IsEqualTo(dataItem);
-            }
-            catch (Exception)
-            {
-                return false;
-            }
+            return TryFind(dataItem, out var found) && found.IsEqualTo(dataItem);
         }
 
         /// <summary>
@@ -589,6 +582,33 @@ public virtual T Find(T dataItem)
             throw new Exception("Item was not found.");
         }
 
+        /// <summary>
+        /// Tries to find the specified item in the list.
+        /// </summary>
+        /// <param name="dataItem">Value to find.</param>
+        /// <param name="found">Value if found, default otherwise.</param>
+        /// <returns>value.</returns>
+        public virtual bool TryFind(T dataItem, out T found)
+        {
+            found = default;
+
+            if (IsEmpty()) return false;
+
+            var currentNode = _firstNode;
+            while (currentNode != null)
+            {
+                if (currentNode.Data.IsEqualTo(dataItem))
+                {
+                    found = dataItem;
+                    return true;
+                }
+
+                currentNode = currentNode.Next;
+            }
+
+            return false;
+        }
+
         /// <summary>
         /// Tries to find a match for the predicate. Returns true if found; otherwise false.
         /// </summary>