using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
public class Test
{
	public static void Main()
	{
        var researchTin = new Research  { Name = "Tin" };
        var researchFire = new Research  { Name = "Fire" };
        var researchWater = new Research  { Name = "Water" };
        var researchIron = new Research  { Name = "Iron" };
        var researchSteam = new Research  { Name = "Steam" };
 
        Dictionary<Research, List<Research>> requiredResearches = 
            new Dictionary<Research, List<Research>>();
 
        var req = new Research[] { researchTin };
        requiredResearches.Add(researchIron, req.ToList());
 
        req = new Research[] { researchFire, researchWater, researchIron };
        requiredResearches.Add(researchSteam, req.ToList());
 
 
        var playerResearches = new List<Research>();
        playerResearches.Add(researchFire);
        //playerResearches.Add(researchWater);
        //playerResearches.Add(researchTin);
 
        var chain = GetReq(requiredResearches, researchSteam);
 
        var missing = chain.Where (c => playerResearches.Where (r => r == c).Any () == false).Distinct();
        foreach(var miss in missing)
        {
            Console.WriteLine(miss.Name);
        }
    }
 
    public static IList<Research> GetReq(Dictionary<Research, List<Research>> reqs, Research target)
    {
        var chain = new List<Research>();
        if(reqs.ContainsKey(target))
        {
            foreach(var item in reqs[target])
            {
                chain.Add(item);
                chain.AddRange(GetReq(reqs, item));
            }
        }
        return chain;
    }
}
 
public class Element
{
}
 
public class Research
{
    public string Name { get; set; }
}
 

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

bnVsbA==

null