Fix DFS infinite loop

Set processed tiles as explored

main.cc

@@ -136,14 +136,14 @@ class World
 		}
 
 		// Mark a list of points in the world
-		void markAll(const list<unsigned int>& path, int value = 2) {
+		void markAll(const list<unsigned int>& path, int value = TRACE) {
 			for (auto tile : path) {
 				markOne(tile, value);
 			}
 		}
 
 		// Mark a point in the world
-		void markOne(unsigned int tile, int value = 3) {
+		void markOne(unsigned int tile, int value = ORIGIN) {
 			board[tile] = value;
 		}
 
@@ -188,6 +188,9 @@ class World
 				// Build path
 				path.push_back(current);
 
+				// Current tile is now processed
+				explored[current] = true;
+
 
 			} while (!r && !open.empty());