public void AddAfter(CircularLinkedListNode <T> node, CircularLinkedListNode <T> newNode)
{
newNode.Next = node.Next;
newNode.Previous = node;
node.Next.Previous = newNode;
node.Next = newNode;
}
/// <inheritdoc />
public override string Part2()
{
List <int> cupValues = new List <int>(Input.Select(c => int.Parse(c.ToString())));
while (cupValues.Count < 1_000_000)
{
cupValues.Add(cupValues.Count + 1);
}
CircularLinkedList <int> cups = new CircularLinkedList <int>(cupValues);
Dictionary <int, CircularLinkedListNode <int> > lookUp = new Dictionary <int, CircularLinkedListNode <int> >();
foreach (CircularLinkedListNode <int> node in cups.Nodes)
{
lookUp.Add(node.Value, node);
}
CircularLinkedListNode <int> currentNode = cups.First;
for (int i = 0; i < 10_000_000; i++)
{
List <CircularLinkedListNode <int> > pickUp = new List <CircularLinkedListNode <int> >
{
currentNode.Next,
currentNode.Next.Next,
currentNode.Next.Next.Next,
};
int destinationValue = currentNode.Value == 1 ? cups.Nodes.Count : currentNode.Value - 1;
while (pickUp[0].Value == destinationValue ||
pickUp[1].Value == destinationValue ||
pickUp[2].Value == destinationValue)
{
destinationValue--;
if (destinationValue == 0)
{
destinationValue = cups.Nodes.Count;
}
}
CircularLinkedListNode <int> destination = lookUp[destinationValue];
cups.Remove(pickUp[0]);
cups.Remove(pickUp[1]);
cups.Remove(pickUp[2]);
cups.AddAfter(destination, pickUp[0]);
cups.AddAfter(pickUp[0], pickUp[1]);
cups.AddAfter(pickUp[1], pickUp[2]);
currentNode = currentNode.Next;
}
long output = (long)lookUp[1].Next.Value * lookUp[1].Next.Next.Value;
return(output.ToString());
}
public CircularLinkedList(List <T> values)
{
CircularLinkedListNode <T> first = new CircularLinkedListNode <T>(values[0]);
CircularLinkedListNode <T> last = new CircularLinkedListNode <T>(values[values.Count - 1]);
first.Next = last;
first.Previous = last;
last.Next = first;
last.Previous = first;
Nodes.Add(first);
Nodes.Add(last);
for (int i = 1; i < values.Count - 1; i++)
{
CircularLinkedListNode <T> newNode = new CircularLinkedListNode <T>(values[i]);
Nodes.Add(newNode);
AddAfter(last.Previous, newNode);
}
}
public void Remove(CircularLinkedListNode <T> node)
{
node.Next.Previous = node.Previous;
node.Previous.Next = node.Next;
}
