using System;   

using System.Collections.Generic;

​

class Neuron {

    public List<Neuron> inputs = new List<Neuron>();

    public int id;

    public Neuron(int id) {

        this.id = id;   

    }

}

​

public class Program {

​

    static Dictionary<int, Neuron> neuronDict = new Dictionary<int, Neuron>();

    static HashSet<Neuron> passedNeurons = new HashSet<Neuron>();

    public static void Main() {

        for (int i = 0; i < 6; i++) {

            neuronDict.Add(i, new Neuron(i));

        }

        /**

         *     5

         *   / |

         * 2 - 4  0

         * |      |

         * 3      1

         *

         */

        AddConnection(0, 1);

        AddConnection(2, 3);

        AddConnection(5, 2);

        AddConnection(4, 5);

        AddConnection(2, 4);

        foreach(KeyValuePair<int, Neuron> neuron in neuronDict) {       

            Console.WriteLine("Neuron "+ neuron.Key);

            Process(neuron.Value);

        }

    }

    static void Process(Neuron neuron) {

        //PrintInputs(neuron.id, neuron);

        passedNeurons.Add(neuron);

        foreach (Neuron input in neuron.inputs) {

            Console.WriteLine("    Querying "+ input.id);

            if (!passedNeurons.Contains(input)) {

                passedNeurons.Add(input);

                Console.WriteLine("    Processing "+ input.id);

                Process(input);

​

                Console.WriteLine("    Adding " + input.id +"'s value");    

            }

        }

​

    }

    static void PrintInputs(int id, Neuron neuron) {

        Console.WriteLine("Neuron "+ id);

        for(int i = 0; i < neuron.inputs.Count; i++) 

            Console.WriteLine("    "+neuron.inputs[i].id + " -> " + id);

    }   

    static void AddConnection(int outputNeuron, int inputNeuron) {

        neuronDict[inputNeuron].inputs.Add(neuronDict[outputNeuron]);

    }

}