Add MatrixGraphs

Author: MaengMaeng

Data Structures/Graphs/MatrixGraphs.java

@@ -0,0 +1,145 @@
+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
+     * verticies 
+     *
+     * @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
+     * verticies 
+     *
+     * @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 verticies in the graph and their adjacencies
+     * 
+     * @return returns a string describing this graph
+     */
+	public String toString() {
+		String s = new 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;
+	}
+
+}