D20.1 OK

D20.1/Program.cs

@@ -113,7 +113,7 @@ namespace D20._1
             file.Close();
 
             //regex = @"^ENNWSWW(NEWS|)SSSEEN(WNSE|)EE(SWEN|)NNN$";
-            regex = @"^WSSEESWWWNW(S|NENNEEEENN(ESSSSW(NWSW|SSEN)|WSWWN(E|WWS(E|SS))))$";
+            //regex = @"^WSSEESWWWNW(S|NENNEEEENN(ESSSSW(NWSW|SSEN)|WSWWN(E|WWS(E|SS))))$";
             //regex = @"^N(EEENWWW|N)$";
 
             regex = regex.TrimStart('^').TrimEnd('$');
@@ -140,20 +140,22 @@ namespace D20._1
 
             Console.WriteLine(sw.ElapsedMilliseconds);
 
-            int max = 0;
+            Dictionary<(int x, int y), int> positions = new Dictionary<(int x, int y), int>();
             foreach (var path in root.Possibilities)
             {
-                var r = GetResult(path);
-                if (r > max) max = r;
+                TestResult(path, positions);
             }
 
+            int max = positions.Max(p => p.Value);
             Console.WriteLine(max);
         }
 
-        private static int GetResult(string str)
+        private static void TestResult(string str, Dictionary<(int x, int y), int> positions)
         {
             (int x, int y) pos = (0, 0);
-            HashSet<((int x, int y) from, (int x, int y) to)> doors = new HashSet<((int x, int y) from, (int x, int y) to)>();
+            int dist = 0;
+
+            positions.TryAdd(pos, 0);
             foreach (var c in str)
             {
                 var bpos = pos;
@@ -165,71 +167,11 @@ namespace D20._1
                     case 'E': pos.x += 1; break;
                 }
 
-                doors.Add((bpos, pos));
-                doors.Add((pos, bpos));
+                dist++;
+                if (positions.TryAdd(pos, dist) == false)
+                    dist = Math.Min(dist + 1, positions[pos]);
+                positions[pos] = dist;
             }
-
-            return GetBreadthFirstSearch(doors, pos);
-        }
-
-
-        // https://en.wikipedia.org/wiki/Breadth-first_search
-        private static int GetBreadthFirstSearch(HashSet<((int x, int y) from, (int x, int y) to)> doors, (int x, int y) togo)
-        {
-            var nodesToVisit = new Queue<(int x, int y)>();
-            var visitedNodes = new HashSet<(int x, int y)>();
-            var meta = new Dictionary<(int x, int y), (int x, int y)>()
-                    {
-                        { (0, 0), (0, 0) }
-                    };
-
-            nodesToVisit.Enqueue((0, 0));
-
-            while (nodesToVisit.Count > 0)
-            {
-                var node = nodesToVisit.Dequeue();
-
-                // Found it!
-                if (node == togo)
-                {
-                    var count = GetActionList(togo, meta, node);
-                    return count;
-                }
-
-                foreach ((int mx, int my) mv in new []{ (0, -1), (1, 0), (0, 1), (-1, 0) })
-                {
-                    (int x, int y) successor = (node.x + mv.mx, node.y + mv.my);
-
-                    // Continue if no door exist
-                    if (doors.Contains((node, successor)) == false) continue;
-
-                    if (visitedNodes.Contains(successor)) continue;
-
-                    if (nodesToVisit.Contains(successor) == false)
-                    {
-                        meta.TryAdd(successor, mv);
-                        nodesToVisit.Enqueue(successor);
-                    }
-                }
-
-                visitedNodes.Add(node);
-            }
-
-            return -1;
-        }
-
-        private static int GetActionList((int x, int y) root, Dictionary<(int x, int y), (int x, int y)> meta, (int x, int y) node)
-        {
-            var actionList = new List<(int x, int y)>();
-
-            while (meta[node] != (0, 0))
-            {
-                var action = meta[node];
-                node = (node.x - action.x, node.y - action.y);
-                actionList.Add(action);
-            }
-
-            return actionList.Count;
         }
     }
 }