style: Apply Java code style guidelines

Author: Siddhram

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

@@ -52,7 +52,7 @@ private TopologicalSort() {
      * @throws IllegalArgumentException if edges is null or contains invalid
      *                                  vertices
      */
-    public static int[] sort(int numVertices, List<int[]> edges) {
+    public static int[] sort(int numVertices, Iterable<int[]> edges) {
         if (edges == null) {
             throw new IllegalArgumentException("Edge list must not be null");
         }

src/test/java/com/thealgorithms/graph/TopologicalSortTest.java

@@ -6,6 +6,7 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import org.junit.jupiter.api.DisplayName;
@@ -16,16 +17,19 @@ class TopologicalSortTest {
     @Test
     @DisplayName("Simple DAG returns correct ordering")
     void simpleDAG() {
-        List<int[]> edges = Arrays.asList(new int[] { 0, 1 }, new int[] { 0, 2 }, new int[] { 1, 3 },
-                new int[] { 2, 3 });
+        List<int[]> edges = new ArrayList<>();
+        edges.add(new int[] { 0, 1 });
+        edges.add(new int[] { 0, 2 });
+        edges.add(new int[] { 1, 3 });
+        edges.add(new int[] { 2, 3 });
         int[] result = TopologicalSort.sort(4, edges);
         assertArrayEquals(new int[] { 0, 1, 2, 3 }, result);
     }
 
     @Test
     @DisplayName("Empty graph returns valid ordering")
     void emptyGraph() {
-        List<int[]> edges = Arrays.asList();
+        List<int[]> edges = new ArrayList<>();
         int[] result = TopologicalSort.sort(3, edges);
         assertEquals(3, result.length);
         // Any permutation is valid for empty graph
@@ -35,7 +39,10 @@ void emptyGraph() {
     @Test
     @DisplayName("Graph with cycle returns null")
     void graphWithCycle() {
-        List<int[]> edges = Arrays.asList(new int[] { 0, 1 }, new int[] { 1, 2 }, new int[] { 2, 0 });
+        List<int[]> edges = new ArrayList<>();
+        edges.add(new int[] { 0, 1 });
+        edges.add(new int[] { 1, 2 });
+        edges.add(new int[] { 2, 0 });
         assertNull(TopologicalSort.sort(3, edges));
     }
 
@@ -44,11 +51,11 @@ void graphWithCycle() {
     void coursePrerequisites() {
         // Example: Course prerequisites where edge [a,b] means course a must be taken
         // before b
-        List<int[]> edges = Arrays.asList(new int[] { 1, 0 }, // Calculus I -> Calculus II
-                new int[] { 2, 0 }, // Linear Algebra -> Calculus II
-                new int[] { 1, 3 }, // Calculus I -> Differential Equations
-                new int[] { 2, 3 } // Linear Algebra -> Differential Equations
-        );
+        List<int[]> edges = new ArrayList<>();
+        edges.add(new int[] { 1, 0 }); // Calculus I -> Calculus II
+        edges.add(new int[] { 2, 0 }); // Linear Algebra -> Calculus II
+        edges.add(new int[] { 1, 3 }); // Calculus I -> Differential Equations
+        edges.add(new int[] { 2, 3 }); // Linear Algebra -> Differential Equations
         List<Integer> result = TopologicalSort.sortAndDetectCycle(4, edges);
         // Either [1,2,0,3] or [2,1,0,3] is valid
         assertEquals(4, result.size());
@@ -62,8 +69,8 @@ void coursePrerequisites() {
     @Test
     @DisplayName("Invalid vertex throws exception")
     void invalidVertex() {
-        List<int[]> edges = Arrays.asList(new int[] { 0, 5 } // Vertex 5 is invalid for a graph with 3 vertices
-        );
+        List<int[]> edges = new ArrayList<>();
+        edges.add(new int[] { 0, 5 }); // Vertex 5 is invalid for a graph with 3 vertices
         assertThrows(IllegalArgumentException.class, () -> TopologicalSort.sort(3, edges));
     }
 
@@ -76,7 +83,10 @@ void nullEdgeList() {
     @Test
     @DisplayName("sortAndDetectCycle throws exception for cyclic graph")
     void detectCycleThrowsException() {
-        List<int[]> edges = Arrays.asList(new int[] { 0, 1 }, new int[] { 1, 2 }, new int[] { 2, 0 });
+        List<int[]> edges = new ArrayList<>();
+        edges.add(new int[] { 0, 1 });
+        edges.add(new int[] { 1, 2 });
+        edges.add(new int[] { 2, 0 });
         assertThrows(IllegalArgumentException.class, () -> TopologicalSort.sortAndDetectCycle(3, edges));
     }
 }