public void ProblemOne()
{
var tubes = ParseInput(Input);
//Find start pos
var position = new Vector2i(0, 0);
var steps = 0;
var direction = Direction.Down;
for (int x = 0; x < tubes.GetLength(0); x++)
{
if (tubes[x, 0] == '|')
{
position.X = x;
break;
}
}
var letters = new List <char>();
while (true)
{
var pre = position.Clone();
var c = tubes[position.X, position.Y];
if (c == ' ')
{
//end
_cashedSteps = steps;
var result = string.Join(string.Empty, letters);
Console.WriteLine(result);
return;
}
if (char.IsLetter(c))
{
letters.Add(c);
if (direction == Direction.Down || direction == Direction.Up)
{
position.Y += direction == Direction.Down ? 1 : -1;
}
if (direction == Direction.Left || direction == Direction.Right)
{
position.X += direction == Direction.Right ? 1 : -1;
}
steps++;
}
//Look downwards or upwards
if (c == '|')
{
position.Y += direction == Direction.Down ? 1 : -1;
steps++;
var nextChar = tubes[position.X, position.Y];
if (nextChar == '-')
{
//Need to skip over another pipe
position.Y += direction == Direction.Down ? 1 : -1;
steps++;
}
}
if (c == '-')
{
position.X += direction == Direction.Right ? 1 : -1;
steps++;
var nextChar = tubes[position.X, position.Y];
if (nextChar == '|')
{
//Need to skip over another pipe
position.X += direction == Direction.Right ? 1 : -1;
steps++;
}
}
if (c == '+')
{
//Dont go in reverse
var reverseDirection = direction.RotateLeft().RotateLeft();
List <(Direction direction, Vector2i vector)> adjacent = _adjacentIndices.Where(i => i.direction != reverseDirection).Select(i => (i.direction, position.Add(i.vector))).ToList();
foreach (var p in adjacent)
{
if (p.vector.X > 0 && p.vector.Y > 0 && p.vector.X < tubes.GetLength(0) && p.vector.Y < tubes.GetLength(1) && tubes[p.vector.X, p.vector.Y] != ' ')
{
position = p.vector;
direction = p.direction;
steps++;
}
}
}
if (pre.Equals(position))
{
//not moved. Problem detected.
throw new Exception();
}
}
}
