public static ulong Solve(string[] input)
{
(List <MultiRange> rules, Ticket yourTicket, List <Ticket> nearbyTickets) = Part1.Solution.ParseInput(input);
List <Ticket> filteredTickets = nearbyTickets.Where(t => !t.IsError(rules)).ToList();
filteredTickets.Add(yourTicket);
bool[,] whichRulesWorkInWhichIndex = new bool[rules.Count, rules.Count];
for (int i = 0; i < rules.Count; ++i)
{
for (int j = 0; j < rules.Count; ++j)
{
whichRulesWorkInWhichIndex[i, j] = filteredTickets.All(t => rules[i].IsInRange(t.Numbers[j]));
}
}
MultiRange[] orderedRules = new MultiRange[rules.Count];
while (orderedRules.Any(rule => rule == null))
{
for (int i = 0; i < rules.Count; ++i)
{
if (!orderedRules.Contains(rules[i]))
{
for (int j = 0; j < rules.Count; ++j)
{
if (orderedRules[j] == null && whichRulesWorkInWhichIndex[i, j] && !Enumerable.Range(0, rules.Count).Where(k => k != j).Any(k => whichRulesWorkInWhichIndex[i, k] && orderedRules[k] == null))
{
orderedRules[j] = rules[i];
}
}
}
}
}
ulong product = 1;
for (int i = 0; i < rules.Count; ++i)
{
if (orderedRules[i].Field.StartsWith("departure"))
{
product *= (ulong)yourTicket.Numbers[i];
}
}
return(product);
}
