package DataStructures.Graphs;

public class MatrixGraphs {

 public static void main(String args[]) {
 AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph(10);
 graph.addEdge(1, 2);
 graph.addEdge(1, 5);
 graph.addEdge(2, 5);
 graph.addEdge(1, 2);
 graph.addEdge(2, 3);
 graph.addEdge(3, 4);
 graph.addEdge(4, 1);
 graph.addEdge(2, 3);
 System.out.println(graph);
 }

}

class AdjacencyMatrixGraph {
 private int _numberOfVertices;
 private int _numberOfEdges;
 private int[][] _adjacency;

 static final int EDGE_EXIST = 1;
 static final int EDGE_NONE = 0;

 public AdjacencyMatrixGraph(int givenNumberOfVertices) {
 this.setNumberOfVertices(givenNumberOfVertices);
 this.setNumberOfEdges(0);
 this.setAdjacency(new int[givenNumberOfVertices][givenNumberOfVertices]);
 for (int i = 0; i < givenNumberOfVertices; i++) {
 for (int j = 0; j < givenNumberOfVertices; j++) {
 this.adjacency()[i][j] = AdjacencyMatrixGraph.EDGE_NONE;
 }
 }
 }

 private void setNumberOfVertices(int newNumberOfVertices) {
 this._numberOfVertices = newNumberOfVertices;
 }

 public int numberOfVertices() {
 return this._numberOfVertices;
 }

 private void setNumberOfEdges(int newNumberOfEdges) {
 this._numberOfEdges = newNumberOfEdges;
 }

 public int numberOfEdges() {
 return this._numberOfEdges;
 }

 private void setAdjacency(int[][] newAdjacency) {
 this._adjacency = newAdjacency;
 }

 private int[][] adjacency() {
 return this._adjacency;
 }

 private boolean adjacencyOfEdgeDoesExist(int from, int to) {
 return (this.adjacency()[from][to] != AdjacencyMatrixGraph.EDGE_NONE);
 }

 public boolean vertexDoesExist(int aVertex) {
 if (aVertex >= 0 && aVertex < this.numberOfVertices()) {
 return true;
 } else {
 return false;
 }
 }

 public boolean edgeDoesExist(int from, int to) {
 if (this.vertexDoesExist(from) && this.vertexDoesExist(to)) {
 return (this.adjacencyOfEdgeDoesExist(from, to));
 }

 return false;
 }

 /**
 * This method adds an edge to the graph between two specified
 * vertices
 *
 * @param from the data of the vertex the edge is from
 * @param to the data of the vertex the edge is going to
 * @return returns true if the edge did not exist, return false if it already did
 */
 public boolean addEdge(int from, int to) {
 if (this.vertexDoesExist(from) && this.vertexDoesExist(to)) {
 if (!this.adjacencyOfEdgeDoesExist(from, to)) {
 this.adjacency()[from][to] = AdjacencyMatrixGraph.EDGE_EXIST;
 this.adjacency()[to][from] = AdjacencyMatrixGraph.EDGE_EXIST;
 this.setNumberOfEdges(this.numberOfEdges() + 1);
 return true;
 }
 }

 return false;
 }

 /**
 * this method removes an edge from the graph between two specified
 * vertices
 *
 * @param from the data of the vertex the edge is from
 * @param to the data of the vertex the edge is going to
 * @return returns false if the edge doesn't exist, returns true if the edge exists and is removed
 */
 public boolean removeEdge(int from, int 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;
 this.setNumberOfEdges(this.numberOfEdges() - 1);
 return true;
 }
 }
 return false;
 }

 /**
 * this gives a list of vertices in the graph and their adjacencies
 *
 * @return returns a string describing this graph
 */
 public String toString() {
 String s = " ";
 for (int i = 0; i < this.numberOfVertices(); i++) {
 s = s + String.valueOf(i) + " ";
 }
 s = s + " \n";

 for (int i = 0; i < this.numberOfVertices(); i++) {
 s = s + String.valueOf(i) + " : ";
 for (int j = 0; j < this.numberOfVertices(); j++) {
 s = s + String.valueOf(this._adjacency[i][j]) + " ";
 }
 s = s + "\n";
 }
 return s;
 }

}