Sep 28, 2017 · Sep 28, 2017 · Sep 28, 2017
diff --git a/data_structures/Graphs/Graphs.java b/data_structures/Graphs/Graphs.java
 import java.util.ArrayList;
 import java.lang.StringBuilder;

 /**
 * This class implements the Graph data structure
 * using the classes Graph and Graphs.
 *
 * @author Zachary Jones
 *
 */
 class Graph {
 class AdjacencyListGraph<E extends Comparable<E>> {

 }
    ArrayList<Vertex> verticies;

    public AdjacencyListGraph() {
        verticies = new ArrayList<>();
    }

    private class Vertex {
        E data;
        ArrayList<Vertex> adjacentVerticies;

        public Vertex(E data) {
            adjacentVerticies = new ArrayList<>();
            this.data = data;
        }

 /**
 * This class is used to test the Graph
 * class above.
 *
 * @author Zachary Jones
 *
 */
        public boolean addAdjacentVertex(Vertex to) {
            for (Vertex v: adjacentVerticies) {
                if (v.data.compareTo(to.data) == 0) {
                    return false; // the edge already exists
                }
            }
            return adjacentVerticies.add(to); // this will return true;
        }

        public boolean removeAdjacentVertex(E to) {
            // use indexes here so it is possible to
            // remove easily without implementing
            // equals method that ArrayList.remove(Object o) uses
            for (int i = 0; i < adjacentVerticies.size(); i++) {
                if (adjacentVerticies.get(i).data.compareTo(to) == 0) {
                    adjacentVerticies.remove(i);
                    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(E from, E to) {
        Vertex fromV = null;
        for (Vertex v: verticies) {
            if (from.compareTo(v.data) == 0) {
                fromV = v;
                break;
            }
        }
        if (fromV == null) return false;
        return fromV.removeAdjacentVertex(to);
    }
    /**
     * 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(E from, E to) {
        Vertex fromV = null, toV = null;
        for (Vertex v: verticies) {
            if (from.compareTo(v.data) == 0) { // see if from vertex already exists
                fromV = v;
            } else if (to.compareTo(v.data) == 0) { // see if to vertex already exists
                toV = v;
            }
            if (fromV != null && toV != null) break; // both nodes exist so stop searching
        }
        if (fromV == null) {
            fromV = new Vertex(from);
            verticies.add(fromV);
        }
        if (toV == null) {
            toV = new Vertex(to);
            verticies.add(toV);
        }
        return fromV.addAdjacentVertex(toV);
    }

    /**
     * this gives a list of verticies in the graph and their adjacencies
     *
     * @return returns a string describing this graph
     */
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Vertex v: verticies) {
            sb.append("Vertex: ");
            sb.append(v.data);
            sb.append("\n");
            sb.append("Adjacent verticies: ");
            for (Vertex v2: v.adjacentVerticies) {
                sb.append(v2.data);
                sb.append(" ");
            }
            sb.append("\n");
        }
        return sb.toString();
    }
 }

 public class Graphs {

 /**
 * Main method
 *
 * @param args Command line arguments
 */
 public static void main(String args[]) {

 }
 AdjacencyListGraph<Integer> graph = new AdjacencyListGraph<>();
        assert graph.addEdge(1, 2);
        assert graph.addEdge(1, 5);
        assert graph.addEdge(2, 5);
    assert !graph.addEdge(1, 2);
        assert graph.addEdge(2, 3);
        assert graph.addEdge(3, 4);
        assert graph.addEdge(4, 1);
        assert !graph.addEdge(2, 3);
        System.out.println(graph);
    }

 }
Original file line number	Diff line number	Diff line change
		@@ -1,32 +1,129 @@
		import java.util.ArrayList;
		import java.lang.StringBuilder;

		/**
		* This class implements the Graph data structure
		* using the classes Graph and Graphs.
		*
		* @author Zachary Jones
		*
		*/
		class Graph {
		class AdjacencyListGraph<E extends Comparable<E>> {

		}
		ArrayList<Vertex> verticies;

		public AdjacencyListGraph() {
		verticies = new ArrayList<>();
		}

		private class Vertex {
		E data;
		ArrayList<Vertex> adjacentVerticies;

		public Vertex(E data) {
		adjacentVerticies = new ArrayList<>();
		this.data = data;
		}

		/**
		* This class is used to test the Graph
		* class above.
		*
		* @author Zachary Jones
		*
		*/
		public boolean addAdjacentVertex(Vertex to) {
		for (Vertex v: adjacentVerticies) {
		if (v.data.compareTo(to.data) == 0) {
		return false; // the edge already exists
		}
		}
		return adjacentVerticies.add(to); // this will return true;
		}

		public boolean removeAdjacentVertex(E to) {
		// use indexes here so it is possible to
		// remove easily without implementing
		// equals method that ArrayList.remove(Object o) uses
		for (int i = 0; i < adjacentVerticies.size(); i++) {
		if (adjacentVerticies.get(i).data.compareTo(to) == 0) {
		adjacentVerticies.remove(i);
		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(E from, E to) {
		Vertex fromV = null;
		for (Vertex v: verticies) {
		if (from.compareTo(v.data) == 0) {
		fromV = v;
		break;
		}
		}
		if (fromV == null) return false;
		return fromV.removeAdjacentVertex(to);
		}
		/**
		* 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(E from, E to) {
		Vertex fromV = null, toV = null;
		for (Vertex v: verticies) {
		if (from.compareTo(v.data) == 0) { // see if from vertex already exists
		fromV = v;
		} else if (to.compareTo(v.data) == 0) { // see if to vertex already exists
		toV = v;
		}
		if (fromV != null && toV != null) break; // both nodes exist so stop searching
		}
		if (fromV == null) {
		fromV = new Vertex(from);
		verticies.add(fromV);
		}
		if (toV == null) {
		toV = new Vertex(to);
		verticies.add(toV);
		}
		return fromV.addAdjacentVertex(toV);
		}

		/**
		* this gives a list of verticies in the graph and their adjacencies
		*
		* @return returns a string describing this graph
		*/
		public String toString() {
		StringBuilder sb = new StringBuilder();
		for (Vertex v: verticies) {
		sb.append("Vertex: ");
		sb.append(v.data);
		sb.append("\n");
		sb.append("Adjacent verticies: ");
		for (Vertex v2: v.adjacentVerticies) {
		sb.append(v2.data);
		sb.append(" ");
		}
		sb.append("\n");
		}
		return sb.toString();
		}
		}

		public class Graphs {

		/**
		* Main method
		*
		* @param args Command line arguments
		*/
		public static void main(String args[]) {

		}
		AdjacencyListGraph<Integer> graph = new AdjacencyListGraph<>();
		assert graph.addEdge(1, 2);
		assert graph.addEdge(1, 5);
		assert graph.addEdge(2, 5);
		assert !graph.addEdge(1, 2);
		assert graph.addEdge(2, 3);
		assert graph.addEdge(3, 4);
		assert graph.addEdge(4, 1);
		assert !graph.addEdge(2, 3);
		System.out.println(graph);
		}

		}