added url

Author: amankumar100

src/main/java/com/thealgorithms/tree/GraphTreeCheck.java

@@ -2,6 +2,16 @@
 
 import java.util.Scanner;
 
+/**
+ * Check if an undirected graph is a tree using Depth-First Search (DFS).
+ * A graph is a tree if it is connected and acyclic.
+ * This implementation reads an adjacency matrix as input and verifies both conditions.
+ * 
+ * Wikipedia Reference: https://en.wikipedia.org/wiki/Tree_(graph_theory)
+ * Author: Aman
+ */
+
+
 class GraphTreeCheck {
 
     private static final int MAX = 10;