This is my C# solution using a file IO to read the inputs: <pre><code> using System; using System.Collections.Generic; using System.IO;
namespace Hard212ReverseMaze { class Program { //delegate for an instruction delegate void moveSetDelegate(ref Position p, ref int dx, ref int dy);
static void Main(string[] args)
{
//read input from file
HashSet<Position> allowableSpaces = new HashSet<Position>();
string input;
using (StreamReader sr = new StreamReader(@"C:\Users\Ferdy\Documents\Visual Studio 2013\Projects\Hard-212-ReverseMaze\maze-long.txt"))
{
int height = int.Parse(sr.ReadLine());
for (int i = 0; i < height; i++)
{
string line = sr.ReadLine();
//get set of allowable spaces in the maze
for (int j = 0; j < line.Length; j++)
{
if (line[j] == ' ')
{
allowableSpaces.Add(new Position(j, i));
}
}
}
input = sr.ReadLine();
}
//traverse through set of instructions
int dirX, dirY;
Position pos;
List<moveSetDelegate> moveSet = new List<moveSetDelegate>();
//for each instruction, add a method to the delegate corresponding to the instruction
for (int i = 0; i < input.Length; i++)
{
string curDirection = input[i].ToString();
int moveAmount;
if (int.TryParse(curDirection, out moveAmount))
{
for (int j = 0; j < moveAmount; j++)
{
moveSet.Add(moveForward);
}
}
else
{
if (curDirection == "l")
{
moveSet.Add(turnLeft);
}
else if (curDirection == "r")
{
moveSet.Add(turnRight);
}
}
}
//traverse through possible solutions set
foreach (Position p in allowableSpaces)
{
foreach (int[] dirs in new List<int[]>() {new int[]{0,1}, new int[]{1,0}, new int[]{0,-1}, new int[]{-1,0}})
{
pos = p;
dirX = dirs[0];
dirY = dirs[1];
bool validPath = true;
//for each possible starting solution, invoke the delegate incrementally (hence the list instead of simply adding)
foreach (moveSetDelegate m in moveSet)
{
m(ref pos, ref dirX, ref dirY);
//if we went out of bounds, then break out of the loop because it's not a valid path
if (!allowableSpaces.Contains(pos))
{
validPath = false;
break;
}
}
//if we didn't hit any walls, then we're good to go!
if (validPath)
{
Console.WriteLine(String.Format("Start Position: ({0},{1}); Start Direction: ({2},{3})", p.x, p.y, dirs[0], dirs[1]));
Console.WriteLine(String.Format("End Position: ({0},{1}); End Direction: ({2},{3})", pos.x, pos.y, dirX, dirY));
}
}
}
Console.WriteLine("End of Routine");
Console.ReadKey();
}
static void turnLeft(ref Position p, ref int dx, ref int dy)
{
int temp = dy;
dy = -dx;
dx = temp;
}
static void turnRight(ref Position p, ref int dx, ref int dy)
{
int temp = dx;
dx = -dy;
dy = temp;
}
static void moveForward(ref Position p, ref int dx, ref int dy)
{
p.y += dy;
p.x += dx;
}
}
//convenient struct for a pair of x,y coordinates
struct Position
{
public int x;
public int y;
public Position(int x, int y)
{
this.x = x;
this.y = y;
}
}
} </pre></code>