using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Graph:");

        Graph g = new Graph();

        g.nodes = new List<Node>();

        g.nodes.Add(new Node("A"));

        g.nodes.Add(new Node("B"));

        g.nodes.Add(new Node("C"));

        g.nodes.Add(new Node("D"));

        g.edges = new List<Edge>();

        g.edges.Add(new Edge("ab", "A", "B"));

        g.edges.Add(new Edge("bc", "B", "C"));

        g.Print();      

        Graph.RemoveGraphEntities(g, new List<string>(new string[]{"C", "D"}), new List<string>(new string[]{}));

        g.Print();

    }

}

​

class Edge

{

    public Edge(string id, string startNodeId, string endNodeId)

    {

        this.id = id;

        this.startNodeId = startNodeId;

        this.endNodeId = endNodeId;

    }

​

    public string id;

    public string startNodeId;

    public string endNodeId;

    public void Print()

    {

        Console.WriteLine(String.Format("  Edge {0} between node {1} and {2}", this.id, this.startNodeId, this.endNodeId));

    }

}

​

class Node

{

    public string id;

    public Node(string id)

    {

        this.id = id;

    }

​

    public void Print()

    {

        Console.WriteLine(String.Format(" Node {0}", this.id));

    }

}

​

class Graph

{

    public List<Node> nodes;

    public List<Edge> edges;

    public void Print()

    {

        foreach (Node n in this.nodes)

        {

            n.Print();

        }

​

        foreach (Edge e in this.edges)

        {

            e.Print();

        }

    }

    public static void RemoveGraphEntities(Graph graph, List<string> nodeIdsToRemove, List<string> edgeIdsToRemove)

    {

        Queue<Node> nodeQueue = new Queue<Node>();

        if (null == graph)

        {

            return;

        }

​

        //if nodes to remove not empty then go find all the matching nodes. 

        // For each matching node, remove the edges leading away from the node. 

        // for ech matching node remove the edges leading into the node. 

        //if edgeIds to remove non empty then find all of the matching edges and remove them. 

        // nodeIdToRemove.Length * graph.Nodes ^ 2  * edgeIdsToREmove.Length.

        foreach (string nodeId in nodeIdsToRemove)

        {

            foreach (Node node in graph.nodes)

            {

                //Removed the node

                if (node.id == nodeId)

                {

                    graph.nodes.Remove(node);

                }

​

                // For each matching node, remove the edges leading away from the node. 

                graph.edges.RemoveAll(k => k.startNodeId == nodeId);

                // for ech matching node remove the edges leading into the node. 

                graph.edges.RemoveAll(k => k.endNodeId == nodeId);

            }

        }

​

        foreach (string edgeId in edgeIdsToRemove)

        {

            foreach (Edge edge in graph.edges)

            {

                graph.edges.RemoveAll(k => k.id == edgeId);

            }

        }

    // Alternate approach would be 

    // pick the first node from graph.Nodes push it into a queue 

    // BFS of the graph.    dequieue the element, look up edges array to find all of the nodes that are neighbor of the current node, keep a map for the nodes we have visited. 

    // remove all of the nodes that match nodes to remove at same remove edges from list of edges to remove as well. 

    // Corner 

    // disconnected nodes of the graph. 

    // find all the nodes that are not visited from line 98 to 101, 

    // map not visited nodes against the list of nodesToRemove. 

    }

}