using System;

using System.Collections.Generic;

​

    public class Node

    {

        public Node() // empty, parameterless constructor

        {

​

        }

        //public List<int> FooList { get; set; } = new List<int>(); [from https://tinyurl.com/ycyqq2s2]

        public List<Node> Children{get; set;} = new List<Node>();

        //public List<Node> Children = new List<Node>(); // not sure about auto-implemented property's

                                                       // "get/set" syntax here. Commented-out version

                                                       // gives compiler error. For reason yet unknown,

                                                       // can access property without the {get;set;} initializer.

                                                       // Ok, looks this syntax is in C# 6. Switching to Roslyn 

                                                       // compiler works.

        public long Id{get; set;}

​

        //returns the factorial of the current node id

​

        private long Factorial()                   // original code had no return value for Id > 0

        {

          long factorialValue = 1; 

​

          if(Id != 0)

          {

            for(long i = 1; i <= Id; i++)

            {

              factorialValue = factorialValue * i; // changed Id to i (original code would

            }                                      // have returned Id^Id i.e. 2nd tetration of Id)

          }

          return factorialValue; 

        }

​

        // Fill in the code here to print sum of the factorial of the node and its 

        // children factorial

​

        public long PrintFactorialSum()

        {

          long childFactorialSum = 0;

​

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

          {

            childFactorialSum = childFactorialSum + Children[i].PrintFactorialSum();

          } 

          return (childFactorialSum + Factorial());                                                                                                                                                                                                              

        }

    }

​

public class Program

{

    public static void Main()

    {           

      Node Node_11 = new Node

      {

      Id = 11,

      };        

      Node Node_10 = new Node

      {

      Id = 10,

      };        

      Node Node_8 = new Node

      {

      Id = 8,

      };        

      Node Node_7 = new Node

      {

      Id = 7,

      };    

      Node Node_5 = new Node

      {

      Id = 5,

      };        

      Node Node_3 = new Node

      {

        Id = 3

      };

      Node Node_2 = new Node

      {

        Id = 2

      };        

      Node Node_12 = new Node

      {

      Id = 12,

      Children = {Node_11, Node_10}

      };        

      Node Node_9 = new Node

      {

      Id = 9,

      Children = {Node_8, Node_7}

      };        

      Node Node_4 = new Node

      {

      Id = 4,

      Children = {Node_3, Node_2}

      };        

      Node Node_6 = new Node

      {

      Id = 6,

      Children = {Node_5, Node_4}

      };

      Node Node_13 = new Node

      {

      Id = 13,

      Children = {Node_12, Node_9, Node_6}

      };

      Console.WriteLine("Node 2:  " + Node_2.PrintFactorialSum());

      Console.WriteLine("Node 3:  " + Node_3.PrintFactorialSum());      

      Console.WriteLine("Node 4:  " + Node_4.PrintFactorialSum());      

      Console.WriteLine("Node 5:  " + Node_5.PrintFactorialSum());

      Console.WriteLine("Node 6:  " + Node_6.PrintFactorialSum());      

      Console.WriteLine("Node 7:  " + Node_7.PrintFactorialSum());      

      Console.WriteLine("Node 8:  " + Node_8.PrintFactorialSum());

      Console.WriteLine("Node 9:  " + Node_9.PrintFactorialSum());      

      Console.WriteLine("Node 10: " + Node_10.PrintFactorialSum());     

      Console.WriteLine("Node 11: " + Node_11.PrintFactorialSum());

      Console.WriteLine("Node 12: " + Node_12.PrintFactorialSum());     

      Console.WriteLine("Node 13: " + Node_13.PrintFactorialSum());             

    }

}