public static BigInteger OreRequiredToProduceFuel(BigInteger amount, ChemicalProductionGraph graph)
{
var amountRequired = graph.Nodes().ToDictionary(x => x, x => x == "FUEL" ? amount : 0);
var unfinishedNodes = graph.Nodes().ToHashSet();
while (unfinishedNodes.Any())
{
var nextUnfinishedNodes = new HashSet <string>(unfinishedNodes);
foreach (var node in unfinishedNodes)
{
var parents = graph.InNeighbours(node).Select(x => x.nb);
if (!unfinishedNodes.Intersect(parents).Any())
{
var children = graph.OutNeighbours(node);
BigInteger amountOfBatches = (amountRequired[node] - 1) / graph.BatchSize(node) + 1; //find smallest x s.t. x*batchsize > amountrequired
foreach ((string child, int perbatch) in children)
{
amountRequired[child] += perbatch * amountOfBatches;
}
nextUnfinishedNodes.Remove(node);
}
}
unfinishedNodes = nextUnfinishedNodes;
}
return(amountRequired["ORE"]);
}
protected override void PrepareSolution()
{
cpgraph = new ChemicalProductionGraph(recipes);
}
