public Dist2 Move(Walk w)
{
Dist2 d2 = new Dist2 {
x = x, y = y
};
switch (w.dir)
{
case Directions.North:
d2.y -= w.steps;
return(d2);
case Directions.East:
d2.x += w.steps;
return(d2);
case Directions.South:
d2.y += w.steps;
return(d2);
case Directions.West:
d2.x -= w.steps;
return(d2);
default:
throw new NotImplementedException();
}
}
public static Dist2 operator +(Dist2 d2, Directions dir)
{
Dist2 d22 = new Dist2 {
x = d2.x, y = d2.y
};
switch (dir)
{
case Directions.North:
d22.y--;
return(d22);
case Directions.East:
d22.x++;
return(d22);
case Directions.South:
d22.y++;
return(d22);
case Directions.West:
d22.x--;
return(d22);
default:
throw new NotImplementedException();
}
}
public static void Run()
{
string[] strs = INPUT.Split(new string[] { ", " }, StringSplitOptions.RemoveEmptyEntries);
List <Walk> walks = strs.Aggregate(new List <Walk>(strs.Length), (ws, str) =>
{
ws.Add(new Walk(ws.LastOrDefault(), str));
return(ws);
});
// Part 1
Dist2 part1 = walks.Aggregate(new Dist2 {
x = 0, y = 0
}, (d2, w) => d2.Move(w));
Console.WriteLine("==== Part 1 ====");
Console.WriteLine($"X: {part1.x}");
Console.WriteLine($"Y: {part1.y}");
Console.WriteLine($"Total distance: {Math.Abs(part1.x) + Math.Abs(part1.y)}");
// Part 2
Dist2 part2 = Part2(walks);
Console.WriteLine("==== Part 2 ====");
Console.WriteLine($"X: {part2.x}");
Console.WriteLine($"Y: {part2.y}");
Console.WriteLine($"Total distance: {Math.Abs(part2.x) + Math.Abs(part2.y)}");
}
private static Dist2 Part2(List <Walk> walks)
{
HashSet <Dist2> visited = new HashSet <Dist2>();
Dist2 part2 = new Dist2 {
x = 0, y = 0
};
foreach (var walk in walks)
{
foreach (var i in Enumerable.Range(0, walk.steps))
{
if (!visited.Add(part2 = part2 + walk.dir))
{
return(part2);
}
}
}
return(part2);
}