Fixed Error:(6, 8) java: class algorithm is public, should be declared in a file named algorithm.java. Inside file PrimeFactorization, the name of public class was wrong.

DataStructures/Graphs/MatrixGraphs.java

@@ -127,8 +127,7 @@ class AdjacencyMatrixGraph {
      * @return returns a string describing this graph
      */
     public String toString() {
-        String s = new String();
-        s = "    ";
+        String s = "    ";
         for (int i = 0; i < this.numberOfVertices(); i++) {
             s = s + String.valueOf(i) + " ";
         }