From 74c0180e1cf955207fba7930dea66c94150bcebf Mon Sep 17 00:00:00 2001
From: ShenMian <sms_school@outlook.com>
Date: Sat, 20 Jan 2024 18:41:35 +0800
Subject: [PATCH] feat(solver): add freeze deadlock detection

---
 src/solver/state.rs       | 79 +++++++++++++++++++++++++++++++++------
 src/systems/auto_solve.rs |  3 +-
 src/test.rs               |  4 +-
 3 files changed, 71 insertions(+), 15 deletions(-)

diff --git a/src/solver/state.rs b/src/solver/state.rs
index 7133152..b3cc190 100644
--- a/src/solver/state.rs
+++ b/src/solver/state.rs
@@ -101,23 +101,20 @@ impl State {
                     continue;
                 }
 
-                // TODO: 检测是否会产生新的死锁
                 if self.can_block_crate(&new_crate_position, solver) {
                     continue;
                 }
 
                 let mut new_movements = self.movements.clone();
-                if let Some(path) =
-                    find_path(&self.player_position, &next_player_position, |position| {
-                        self.can_block_player(position, solver)
-                    })
-                {
-                    new_movements.extend(
-                        path.windows(2)
-                            .map(|p| Direction::from_vector(p[1] - p[0]).unwrap())
-                            .map(Movement::with_move),
-                    )
-                }
+                let path = find_path(&self.player_position, &next_player_position, |position| {
+                    self.can_block_player(position, solver)
+                })
+                .unwrap();
+                new_movements.extend(
+                    path.windows(2)
+                        .map(|p| Direction::from_vector(p[1] - p[0]).unwrap())
+                        .map(Movement::with_move),
+                );
                 new_movements.push(Movement::with_push(push_direction));
 
                 // skip tunnels
@@ -138,6 +135,18 @@ impl State {
                 new_crate_positions.remove(crate_position);
                 new_crate_positions.insert(new_crate_position);
 
+                // skip deadlocks
+                if !solver.level.target_positions.contains(&new_crate_position)
+                    && self.is_freeze_deadlock(
+                        &new_crate_position,
+                        &new_crate_positions,
+                        solver,
+                        &mut HashSet::new(),
+                    )
+                {
+                    continue;
+                }
+
                 let new_player_position = new_crate_position - push_direction.to_vector();
 
                 let new_state = State::new(
@@ -174,6 +183,52 @@ impl State {
         instance
     }
 
+    fn is_freeze_deadlock(
+        &self,
+        crate_position: &Vector2<i32>,
+        crate_positions: &HashSet<Vector2<i32>>,
+        solver: &Solver,
+        visited: &mut HashSet<Vector2<i32>>,
+    ) -> bool {
+        if !visited.insert(*crate_position) {
+            return true;
+        }
+
+        for direction in [
+            Direction::Up,
+            Direction::Down,
+            Direction::Left,
+            Direction::Right,
+        ]
+        .chunks(2)
+        {
+            let neighbors = [
+                crate_position + direction[0].to_vector(),
+                crate_position + direction[1].to_vector(),
+            ];
+            if solver
+                .level
+                .get_unchecked(&neighbors[0])
+                .intersects(Tile::Wall)
+                || solver
+                    .level
+                    .get_unchecked(&neighbors[1])
+                    .intersects(Tile::Wall)
+            {
+                continue;
+            }
+            if (crate_positions.contains(&neighbors[0])
+                && self.is_freeze_deadlock(&neighbors[0], crate_positions, solver, visited))
+                || (crate_positions.contains(&neighbors[1])
+                    && self.is_freeze_deadlock(&neighbors[1], crate_positions, solver, visited))
+            {
+                continue;
+            }
+            return false;
+        }
+        return true;
+    }
+
     /// Minimum number of pushes required to complete the level.
     fn lower_bound(&self, solver: &Solver) -> usize {
         *self
diff --git a/src/systems/auto_solve.rs b/src/systems/auto_solve.rs
index eb3c300..668040d 100644
--- a/src/systems/auto_solve.rs
+++ b/src/systems/auto_solve.rs
@@ -12,8 +12,9 @@ pub fn spawn_lowerbound_marks(
     mut board: Query<&mut Board>,
 ) {
     let Board { board, tile_size } = &mut *board.single_mut();
+    let solver = solver_state.solver.lock().unwrap();
 
-    let lowerbounds = solver_state.solver.lock().unwrap().lower_bounds().clone();
+    let lowerbounds = solver.lower_bounds().clone();
     let max_lowerbound = lowerbounds
         .iter()
         .map(|(_, lowerbound)| *lowerbound)
diff --git a/src/test.rs b/src/test.rs
index 4858834..1fcf900 100644
--- a/src/test.rs
+++ b/src/test.rs
@@ -22,8 +22,8 @@ mod tests {
         let levels = Level::load_from_file(Path::new("assets/levels/box_world.xsb")).unwrap();
         let mut failed = 0;
         for i in [
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 18, 19, 21, 24, 28, 29, 31, 34,
-            36, 40, 43, 61, 62, 64, 65, 69, 74, 76, 90, 91,
+            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 21, 24, 28, 30, 31,
+            34, 36, 40, 43, 61, 62, 64, 65, 69, 74, 76, 90, 91,
         ] {
             let level = levels[i].clone();
             let mut solver = Solver::new(level.clone());