Maze gen can now more efficiently produce an interesting map that is fully pathable.

src/algos/maze.cpp

@@ -215,12 +215,11 @@ namespace maze {
 
   void Builder::remove_dead_ends() {
     dbc::check($dead_ends.size() > 0, "you have to run an algo first, no dead_ends to remove");
+
     for(auto at : $dead_ends) {
       for(matrix::compass it{$walls, at.x, at.y}; it.next();) {
-        if($walls[it.y][it.x] == 0) {
-          int diff_x = at.x - it.x;
-          int diff_y = at.y - it.y;
-          $walls[at.y + diff_y][at.x + diff_x] = 0;
+        if($walls[it.y][it.x] == SPACE_VALUE) {
+          punch_dead_end(at.x, at.y, it.x, it.y);
           break;
         }
       }
@@ -404,4 +403,62 @@ namespace maze {
 
     return true;
   }
+
+  void Builder::punch_dead_end(size_t at_x, size_t at_y, size_t x, size_t y) {
+    int diff_x = at_x - x;
+    int diff_y = at_y - y;
+    $walls[at_y + diff_y][at_x + diff_x] = SPACE_VALUE;
+  }
+
+  bool Builder::repair() {
+    // possible fixes
+    // go through each dead end and remove until it works
+    // go through each room and add a door until it works
+    // only find rooms that are unpathable and fix them
+    // walk the path deleting dead ends at the end of the path
+    std::vector<Point> removed_ends;
+    bool now_valid = false;
+
+    for(auto& at : $dead_ends) {
+      // punch a hole for this dead end
+      for(matrix::compass it{$walls, at.x, at.y}; it.next();) {
+        if($walls[it.y][it.x] == SPACE_VALUE) {
+          punch_dead_end(at.x, at.y, it.x, it.y);
+          removed_ends.push_back({it.x, it.y});
+          break;
+        }
+      }
+
+      // if that validates it then done
+      if(validate()) {
+        now_valid = true;
+        fmt::println("MID dead_end removed={}, total={}, %={}",
+          removed_ends.size(), $dead_ends.size(),
+          float(removed_ends.size()) / float($dead_ends.size()));
+        break;
+      }
+    }
+
+    // now go back and see if we can add any back
+    int added_back = 0;
+    for(auto& at : removed_ends) {
+      $walls[at.y][at.x] = WALL_VALUE;
+
+      if(!validate()) {
+        $walls[at.y][at.x] = SPACE_VALUE;
+      } else {
+        added_back++;
+      }
+    }
+
+    enclose();
+    now_valid = validate();
+
+    fmt::println("FINAL now_valid={} added_back={} removed={}, total={}, %={}",
+        now_valid, added_back, removed_ends.size() - added_back, $dead_ends.size(),
+        float(removed_ends.size() - added_back) / float($dead_ends.size()));
+
+    // didn't find a way to make it valid
+    return now_valid;
+  }
 }

src/algos/maze.hpp

@@ -40,5 +40,7 @@ namespace maze {
     bool room_should_exist(Room& room, bool allow_dupes=false);
     void make_doors();
     bool validate();
+    bool repair();
+    void punch_dead_end(size_t at_x, size_t at_y, size_t x, size_t y);
   };
 }