private static void MainDay22()
{
var risk = 0;
for (var xIndex = 0; xIndex <= targetX; xIndex++)
{
for (var yIndex = 0; yIndex <= targetY; yIndex++)
{
risk += ErosionLevel(xIndex, yIndex) % 3;
}
}
Console.WriteLine($"Risk level : {risk}");
var visitedRooms = new Dictionary <Coord, int>();
var done = new HashSet <Coord>();
var start = new Coord(0, 0, Equipment.Torch);
minDistToTarget = start.ManhattanDistance(new Coord(targetX, targetY, Equipment.Torch)) * 8;
for (visitedRooms.Add(start, 0);;)
{
var minDist = int.MaxValue;
Coord closestRoom = null;
foreach (var pair in visitedRooms)
{
if (pair.Value < minDist)
{
minDist = pair.Value;
closestRoom = pair.Key;
}
}
visitedRooms.Remove(closestRoom);
done.Add(closestRoom);
if (minDist > minDistToTarget)
{
// we have found the shortest possible path
break;
}
// examine rooms around
if (closestRoom.X > 0)
{
DistToNeighbout(closestRoom, closestRoom.X - 1, closestRoom.Y, minDist, visitedRooms, done);
}
DistToNeighbout(closestRoom, closestRoom.X + 1, closestRoom.Y, minDist, visitedRooms, done);
if (closestRoom.Y > 0)
{
DistToNeighbout(closestRoom, closestRoom.X, closestRoom.Y - 1, minDist, visitedRooms, done);
}
DistToNeighbout(closestRoom, closestRoom.X, closestRoom.Y + 1, minDist, visitedRooms, done);
// stay in place, but change gear
UpdateDistToRoom(closestRoom.ChangeEquipment(), minDist + 7, visitedRooms, done);
}
Console.WriteLine($"Shortest path: {minDistToTarget}");
}