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Add tests, fix removeEdge bug in MatrixGraphs (#5968)

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This commit is contained in:
Hardik Pawar
2024-10-26 23:30:02 +05:30
committed by GitHub
parent a8b8420716
commit cfa35a4fd9
3 changed files with 155 additions and 14 deletions
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1
DIRECTORY.md
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@ -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

28
src/main/java/com/thealgorithms/datastructures/graphs/MatrixGraphs.java
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@ -102,7 +102,7 @@ class AdjacencyMatrixGraph {
/**
* 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 @@ class AdjacencyMatrixGraph {
* 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 @@ class AdjacencyMatrixGraph {
public List<Integer> depthFirstOrder(int startVertex) {
// If the startVertex is invalid, return an empty list
if (startVertex >= vertexCount || startVertex < 0) {
return new ArrayList<Integer>();
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<Integer> orderList = new ArrayList<Integer>();
ArrayList<Integer> orderList = new ArrayList<>();
// Perform our DFS algorithm
depthFirstOrder(startVertex, visited, orderList);
@ -278,18 +278,18 @@ class AdjacencyMatrixGraph {
public List<Integer> breadthFirstOrder(int startVertex) {
// If the specified startVertex is invalid, return an empty list
if (startVertex >= vertexCount || startVertex < 0) {
return new ArrayList<Integer>();
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<Integer> orderList = new ArrayList<Integer>();
ArrayList<Integer> orderList = new ArrayList<>();
// Create a queue for our BFS algorithm and add the startVertex
// to the queue
Queue<Integer> queue = new LinkedList<Integer>();
Queue<Integer> queue = new LinkedList<>();
queue.add(startVertex);
// Continue until the queue is empty
@ -327,19 +327,19 @@ class AdjacencyMatrixGraph {
* @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();
}
}

140
src/test/java/com/thealgorithms/datastructures/graphs/MatrixGraphsTest.java Normal file
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@ -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<Integer> dfs = graph.depthFirstOrder(0);
assertEquals(5, dfs.size());
assertEquals(0, dfs.getFirst());
assertTrue(dfs.containsAll(Arrays.asList(0, 1, 2, 3, 4)));
List<Integer> 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<Integer> bfs = graph.breadthFirstOrder(0);
assertEquals(5, bfs.size());
assertEquals(0, bfs.getFirst());
assertTrue(bfs.containsAll(Arrays.asList(0, 1, 2, 3, 4)));
List<Integer> 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<Integer> dfs = graph.depthFirstOrder(0);
List<Integer> 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<Integer> dfs = graph.depthFirstOrder(0);
List<Integer> 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)));
}
}