Data commit

Task/Maze-generation/C-sharp/maze-generation.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Drawing;
+
+namespace MazeGeneration
+{
+    public static class Extensions
+    {
+        public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> source, Random rng)
+        {
+            var e = source.ToArray();
+            for (var i = e.Length - 1; i >= 0; i--)
+            {
+                var swapIndex = rng.Next(i + 1);
+                yield return e[swapIndex];
+                e[swapIndex] = e[i];
+            }
+        }
+
+        public static CellState OppositeWall(this CellState orig)
+        {
+            return (CellState)(((int) orig >> 2) | ((int) orig << 2)) & CellState.Initial;
+        }
+
+        public static bool HasFlag(this CellState cs,CellState flag)
+        {
+            return ((int)cs & (int)flag) != 0;
+        }
+    }
+
+    [Flags]
+    public enum CellState
+    {
+        Top = 1,
+        Right = 2,
+        Bottom = 4,
+        Left = 8,
+        Visited = 128,
+        Initial = Top | Right | Bottom | Left,
+    }
+
+    public struct RemoveWallAction
+    {
+        public Point Neighbour;
+        public CellState Wall;
+    }
+
+    public class Maze
+    {
+        private readonly CellState[,] _cells;
+        private readonly int _width;
+        private readonly int _height;
+        private readonly Random _rng;
+
+        public Maze(int width, int height)
+        {
+            _width = width;
+            _height = height;
+            _cells = new CellState[width, height];
+            for(var x=0; x<width; x++)
+                for(var y=0; y<height; y++)
+                    _cells[x, y] = CellState.Initial;
+            _rng = new Random();
+            VisitCell(_rng.Next(width), _rng.Next(height));
+        }
+
+        public CellState this[int x, int y]
+        {
+            get { return _cells[x,y]; }
+            set { _cells[x,y] = value; }
+        }
+
+        public IEnumerable<RemoveWallAction> GetNeighbours(Point p)
+        {
+            if (p.X > 0) yield return new RemoveWallAction {Neighbour = new Point(p.X - 1, p.Y), Wall = CellState.Left};
+            if (p.Y > 0) yield return new RemoveWallAction {Neighbour = new Point(p.X, p.Y - 1), Wall = CellState.Top};
+            if (p.X < _width-1) yield return new RemoveWallAction {Neighbour = new Point(p.X + 1, p.Y), Wall = CellState.Right};
+            if (p.Y < _height-1) yield return new RemoveWallAction {Neighbour = new Point(p.X, p.Y + 1), Wall = CellState.Bottom};
+        }
+
+        public void VisitCell(int x, int y)
+        {
+            this[x,y] |= CellState.Visited;
+            foreach (var p in GetNeighbours(new Point(x, y)).Shuffle(_rng).Where(z => !(this[z.Neighbour.X, z.Neighbour.Y].HasFlag(CellState.Visited))))
+            {
+                this[x, y] -= p.Wall;
+                this[p.Neighbour.X, p.Neighbour.Y] -= p.Wall.OppositeWall();
+                VisitCell(p.Neighbour.X, p.Neighbour.Y);
+            }
+        }
+
+        public void Display()
+        {
+            var firstLine = string.Empty;
+            for (var y = 0; y < _height; y++)
+            {
+                var sbTop = new StringBuilder();
+                var sbMid = new StringBuilder();
+                for (var x = 0; x < _width; x++)
+                {
+                    sbTop.Append(this[x, y].HasFlag(CellState.Top) ? "+---" : "+   ");
+                    sbMid.Append(this[x, y].HasFlag(CellState.Left) ? "|   " : "    ");
+                }
+                if (firstLine == string.Empty)
+                    firstLine = "   " + sbTop.ToString();
+                Debug.WriteLine("   " + sbTop + "+");
+                Debug.WriteLine("   " + sbMid + "|");
+            }
+            Debug.WriteLine(firstLine);
+        }
+    }
+
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            var maze = new Maze(20, 20);
+            maze.Display();
+        }
+    }
+}