diff --git a/DIRECTORY.md b/DIRECTORY.md index f8bb3711a664..50f70abb2ed7 100644 --- a/DIRECTORY.md +++ b/DIRECTORY.md @@ -851,6 +851,7 @@ * [KahnsAlgorithmTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/KahnsAlgorithmTest.java) * [KosarajuTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/KosarajuTest.java) * [KruskalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/KruskalTest.java) + * [MatrixGraphsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/MatrixGraphsTest.java) * [TarjansAlgorithmTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/TarjansAlgorithmTest.java) * [WelshPowellTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/graphs/WelshPowellTest.java) * hashmap diff --git a/src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java b/src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java index 902553f9a54c..c1d47df457da 100644 --- a/src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java +++ b/src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java @@ -102,7 +102,7 @@ public int numberOfVertices() { /** * Updates the number of edges in the graph * - * @param newNumberOfEdges + * @param newNumberOfEdges the new number of edges * */ private void setNumberOfEdges(int newNumberOfEdges) { @@ -202,7 +202,7 @@ public boolean addEdge(int from, int to) { * exists and is removed */ public boolean removeEdge(int from, int to) { - if (!this.vertexDoesExist(from) || !this.vertexDoesExist(to)) { + if (this.vertexDoesExist(from) && this.vertexDoesExist(to)) { if (this.adjacencyOfEdgeDoesExist(from, to)) { this.adjacency()[from][to] = AdjacencyMatrixGraph.EDGE_NONE; this.adjacency()[to][from] = AdjacencyMatrixGraph.EDGE_NONE; @@ -223,14 +223,14 @@ public boolean removeEdge(int from, int to) { public List depthFirstOrder(int startVertex) { // If the startVertex is invalid, return an empty list if (startVertex >= vertexCount || startVertex < 0) { - return new ArrayList(); + return new ArrayList<>(); } // Create an array to track the visited vertices boolean[] visited = new boolean[vertexCount]; // Create a list to keep track of the order of our traversal - ArrayList orderList = new ArrayList(); + ArrayList orderList = new ArrayList<>(); // Perform our DFS algorithm depthFirstOrder(startVertex, visited, orderList); @@ -278,18 +278,18 @@ private void depthFirstOrder(int currentVertex, boolean[] visited, List public List breadthFirstOrder(int startVertex) { // If the specified startVertex is invalid, return an empty list if (startVertex >= vertexCount || startVertex < 0) { - return new ArrayList(); + return new ArrayList<>(); } // Create an array to keep track of the visited vertices boolean[] visited = new boolean[vertexCount]; // Create a list to keep track of the ordered vertices - ArrayList orderList = new ArrayList(); + ArrayList orderList = new ArrayList<>(); // Create a queue for our BFS algorithm and add the startVertex // to the queue - Queue queue = new LinkedList(); + Queue queue = new LinkedList<>(); queue.add(startVertex); // Continue until the queue is empty @@ -327,19 +327,19 @@ public List breadthFirstOrder(int startVertex) { * @return returns a string describing this graph */ public String toString() { - String s = " "; + StringBuilder s = new StringBuilder(" "); for (int i = 0; i < this.numberOfVertices(); i++) { - s = s + i + " "; + s.append(i).append(" "); } - s = s + " \n"; + s.append(" \n"); for (int i = 0; i < this.numberOfVertices(); i++) { - s = s + i + " : "; + s.append(i).append(" : "); for (int j = 0; j < this.numberOfVertices(); j++) { - s = s + this.adjMatrix[i][j] + " "; + s.append(this.adjMatrix[i][j]).append(" "); } - s = s + "\n"; + s.append("\n"); } - return s; + return s.toString(); } } diff --git a/src/test/java/com/thealgorithms/datastructures/graphs/MatrixGraphsTest.java b/src/test/java/com/thealgorithms/datastructures/graphs/MatrixGraphsTest.java new file mode 100644 index 000000000000..cc8a2df872ce --- /dev/null +++ b/src/test/java/com/thealgorithms/datastructures/graphs/MatrixGraphsTest.java @@ -0,0 +1,140 @@ +package com.thealgorithms.datastructures.graphs; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertFalse; +import static org.junit.jupiter.api.Assertions.assertTrue; + +import java.util.Arrays; +import java.util.List; +import org.junit.jupiter.api.Test; + +class MatrixGraphsTest { + + @Test + void testGraphConstruction() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + assertEquals(5, graph.numberOfVertices()); + assertEquals(0, graph.numberOfEdges()); + } + + @Test + void testAddEdge() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + assertTrue(graph.addEdge(0, 1)); + assertTrue(graph.edgeDoesExist(0, 1)); + assertTrue(graph.edgeDoesExist(1, 0)); + assertEquals(1, graph.numberOfEdges()); + + // Adding the same edge again should return false + assertFalse(graph.addEdge(0, 1)); + assertFalse(graph.addEdge(5, 1)); + assertFalse(graph.addEdge(-1, 1)); + } + + @Test + void testRemoveEdge() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + graph.addEdge(0, 1); + graph.addEdge(1, 2); + + assertTrue(graph.removeEdge(0, 1)); + assertFalse(graph.edgeDoesExist(0, 1)); + assertFalse(graph.edgeDoesExist(1, 0)); + assertEquals(1, graph.numberOfEdges()); + + assertFalse(graph.removeEdge(0, 3)); + assertFalse(graph.removeEdge(5, 1)); + assertFalse(graph.removeEdge(-1, 1)); + } + + @Test + void testVertexDoesExist() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + assertTrue(graph.vertexDoesExist(0)); + assertTrue(graph.vertexDoesExist(4)); + assertFalse(graph.vertexDoesExist(5)); + assertFalse(graph.vertexDoesExist(-1)); + } + + @Test + void testDepthFirstOrder() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + graph.addEdge(0, 1); + graph.addEdge(0, 2); + graph.addEdge(1, 3); + graph.addEdge(2, 4); + + List dfs = graph.depthFirstOrder(0); + assertEquals(5, dfs.size()); + assertEquals(0, dfs.getFirst()); + + assertTrue(dfs.containsAll(Arrays.asList(0, 1, 2, 3, 4))); + + List emptyDfs = graph.depthFirstOrder(5); + assertTrue(emptyDfs.isEmpty()); + } + + @Test + void testBreadthFirstOrder() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + graph.addEdge(0, 1); + graph.addEdge(0, 2); + graph.addEdge(1, 3); + graph.addEdge(2, 4); + + List bfs = graph.breadthFirstOrder(0); + assertEquals(5, bfs.size()); + assertEquals(0, bfs.getFirst()); + + assertTrue(bfs.containsAll(Arrays.asList(0, 1, 2, 3, 4))); + + List emptyBfs = graph.breadthFirstOrder(5); + assertTrue(emptyBfs.isEmpty()); + } + + @Test + void testToString() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(3); + graph.addEdge(0, 1); + graph.addEdge(1, 2); + + String expected = " 0 1 2 \n" + + "0 : 0 1 0 \n" + + "1 : 1 0 1 \n" + + "2 : 0 1 0 \n"; + + assertEquals(expected, graph.toString()); + } + + @Test + void testCyclicGraph() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(4); + graph.addEdge(0, 1); + graph.addEdge(1, 2); + graph.addEdge(2, 3); + graph.addEdge(3, 0); + + List dfs = graph.depthFirstOrder(0); + List bfs = graph.breadthFirstOrder(0); + + assertEquals(4, dfs.size()); + assertEquals(4, bfs.size()); + assertTrue(dfs.containsAll(Arrays.asList(0, 1, 2, 3))); + assertTrue(bfs.containsAll(Arrays.asList(0, 1, 2, 3))); + } + + @Test + void testDisconnectedGraph() { + AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(5); + graph.addEdge(0, 1); + graph.addEdge(2, 3); + + List dfs = graph.depthFirstOrder(0); + List bfs = graph.breadthFirstOrder(0); + + assertEquals(2, dfs.size()); + assertEquals(2, bfs.size()); + assertTrue(dfs.containsAll(Arrays.asList(0, 1))); + assertTrue(bfs.containsAll(Arrays.asList(0, 1))); + } +}