public static PathResult <GridPoint3D> GetShortestPathThroughMaze(DonutMaze maze)
{
int Heuristic(GridPoint3D point)
{
// We can no longer use a heuristic because the portals make
// it so that the manhattan distance can overestimate the
// remaining distance.
// TODO: Use the distance to the closest portal OR to the
// finish instead (whichever is closer)
if (!maze.IsRecursive)
{
return(0);
}
return(point.Z);
}
int GetEdgeCost(GridPoint3D p1, GridPoint3D p2)
{
return(1);
}
var pathResult = AStar.GetPath(
startPoint: maze.EntrancePoint,
endPoint: maze.ExitPoint,
Heuristic: Heuristic,
GetNeighbors: maze.GetEmptyNeighbors,
GetEdgeCost: GetEdgeCost);
return(pathResult);
}
public static int GetDay20Part1Answer()
{
// In your maze, how many steps does it take to get from the open
// tile marked AA to the open tile marked ZZ?
// Answer: 588
var mazeDefinition = GetDay20Input();
var maze = new DonutMaze(mazeDefinition);
maze.DrawMaze();
var pathResult = GetShortestPathThroughMaze(maze);
var pathString = GetPathString(pathResult, maze);
Console.WriteLine(pathString);
return(pathResult.TotalPathCost);
}
public static int GetDay20Part2Answer()
{
// In your maze, when accounting for recursion, how many steps
// does it take to get from the open tile marked AA to the open
// tile marked ZZ, both at the outermost layer?
// Answer: 6834
var mazeDefinition = GetDay20Input();
var maze = new DonutMaze(mazeDefinition, isRecursive: true);
maze.DrawMaze();
var pathResult = GetShortestPathThroughMaze(maze);
var pathString = GetPathString(pathResult, maze);
Console.WriteLine(pathString);
return(pathResult.TotalPathCost);
}
public static string GetPathString(PathResult <GridPoint3D> pathResult, DonutMaze maze)
{
var result = new StringBuilder();
int stepCount = 0;
foreach (var currentPoint in pathResult.Path)
{
if (maze.PortalCells.ContainsKey(currentPoint.XYPoint))
{
if (result.Length > 0)
{
result.Append(" ---> ");
}
result.Append($"({maze.PortalCells[currentPoint.XYPoint]}, Level: {currentPoint.Z}, Total steps: {stepCount})");
}
stepCount++;
}
return(result.ToString());
}