public override string P2()
{
FastList <int> packages = new(Input.Select(line => int.Parse(line)).OrderByDescending(i => i).ToArray());
int target = packages.Sum() / 4;
List <int[]> sets = new();
CollectSets(packages, target, new(), sets);
FastList <int[]> allSets = new(sets.OrderBy(s => s.Length).ToArray());
int shortestFound = int.MaxValue;
ulong minQE = int.MaxValue;
allSets.ForEachBreakable(group1 =>
{
if (group1.Length > shortestFound)
{
return(false);
}
// Remove all sets that overlap
FastList <int[]> subset1 = allSets.Without(set => Overlap(group1, set));
bool searching = true;
// For each sets in the non-overlapping group... (group2)
subset1.ForEachBreakable(group2 =>
{
// Remove all sets that overlap
FastList <int[]> subset2 = subset1.Without(set => Overlap(group2, set));
subset2.ForEachBreakable(group3 =>
{
FastList <int[]> final = subset2.Without(set => Overlap(group3, set));
if (final.Length > 0)
{
//Console.WriteLine($"{string.Join(" ", group1)} = {Product(group1)}");
shortestFound = group1.Length;
minQE = Math.Min(minQE, Product(group1));
searching = false;
}
return(searching);
});
return(searching);
});
return(true);
});
return(minQE.ToString());
}