Graph.java

package graph_algorithms;

import data_structures.LinkedList;

import java.util.function.BiConsumer;

public abstract class Graph {

 protected final int vertexCount;
 protected final boolean directed;
 protected int edgeCount = 0;

 public Graph(int n, boolean directed) {
 vertexCount = n;
 this.directed = directed;
 }

 protected static void constructExampleGraph(Graph graph) {
 graph.addEdge(0, 1, 1);
 graph.addEdge(1, 2, 2);
 graph.addEdge(2, 3, 3);
 graph.addEdge(3, 1, 4);
 graph.addEdge(3, 0, 5);
 }

 public int getVertexCount() {
 return vertexCount;
 }

 public int getEdgeCount() {
 return edgeCount;
 }

 public void addEdge(int from, int to) {
 addEdge(from, to, 1);
 }

 public void addEdge(int from, int to, double cost) {
 _addEdge(from, to, cost);
 if (!directed) {
 _addEdge(to, from, cost);
 }
 edgeCount++;
 }

 protected abstract void _addEdge(int from, int to, double cost);

 public abstract boolean containsEdge(int from, int to);

 public abstract LinkedList<Integer> outEdges(int vertex); // TODO: Use Dictionary once AVLTree is finished

 public void forEachEdge(BiConsumer<Integer, Integer> action) {
 for (int u = 0; u < vertexCount; ++u) {
 for (int v : this.outEdges(u)) {
 action.accept(u, v);
 }
 }
 }

 public abstract double cost(int from, int to);

 public static class Edge {

 int from;
 int to;

 public Edge(int from, int to) {
 this.from = from;
 this.to = to;
 }

 }
}