fix fast validation

battlesnake/src/bin/seed-cracker.rs

@@ -202,14 +202,20 @@ struct PreparedGame {
     corners: [Option<u8>; 4],
     cardinals: [Option<u8>; 4],
     corner_first: bool,
-    food_spawns: Vec<Option<FoodSpawn>>,
+    food_spawns: Vec<FoodSpawn>,
     food_chance: u8,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 enum FoodSpawn {
+    /// No food was spawned
+    None,
+    /// Some food was spawned because it would go under `min_food` otherwise
     Forced { selected: u16, free_spots: u16 },
+    /// Some food was spawned by chance
     Random { selected: u16, free_spots: u16 },
+    /// No food was spawned because there is no space on the board
+    Blocked,
 }
 
 impl PreparedGame {
@@ -269,9 +275,14 @@ impl PreparedGame {
                 }
             })
             .map(|(previous, next)| {
-                // no new food, no food eaten
-                if previous.board.food == next.board.food {
-                    return None;
+                let mut tmp = next.clone();
+                tmp.board.food.clone_from(&previous.board.food);
+                let heads: Vec<_> = tmp.board.snakes.iter().map(|snake| snake.head).collect();
+                tmp.board.food.retain(|coord| !heads.contains(coord));
+                let free_spots = get_unoccupied_points(&tmp);
+
+                if free_spots.is_empty() {
+                    return FoodSpawn::Blocked;
                 }
 
                 let diff: Vec<_> = next
@@ -282,15 +293,9 @@ impl PreparedGame {
                     .collect();
                 if diff.is_empty() {
                     // We didn't spawn any food. It was only eaten
-                    return None;
+                    return FoodSpawn::None;
                 }
 
-                let mut tmp = next.clone();
-                tmp.board.food.clone_from(&previous.board.food);
-                let heads: Vec<_> = tmp.board.snakes.iter().map(|snake| snake.head).collect();
-                tmp.board.food.retain(|coord| !heads.contains(coord));
-                let free_spots = get_unoccupied_points(&tmp);
-
                 let selected = free_spots
                     .iter()
                     .position(|spot| spot == diff[0])
@@ -299,15 +304,15 @@ impl PreparedGame {
                 let free_spots = free_spots.len().az();
 
                 if next.board.food.len() == usize::from(food_min) {
-                    Some(FoodSpawn::Forced {
+                    FoodSpawn::Forced {
                         selected,
                         free_spots,
-                    })
+                    }
                 } else {
-                    Some(FoodSpawn::Random {
+                    FoodSpawn::Random {
                         selected,
                         free_spots,
-                    })
+                    }
                 }
             })
             .collect();
@@ -360,16 +365,14 @@ impl PreparedGame {
             let rand = get_rand(input_rand, seed, (turn).az());
 
             match spawn {
-                Some(
-                    spawn @ (FoodSpawn::Forced {
-                        selected,
-                        free_spots,
-                    }
-                    | FoodSpawn::Random {
-                        selected,
-                        free_spots,
-                    }),
-                ) => {
+                spawn @ (FoodSpawn::Forced {
+                    selected,
+                    free_spots,
+                }
+                | FoodSpawn::Random {
+                    selected,
+                    free_spots,
+                }) => {
                     if matches!(spawn, FoodSpawn::Random { .. })
                         && 100 - rand.int_n(100) >= usize::from(self.food_chance)
                     {
@@ -387,13 +390,17 @@ impl PreparedGame {
                     }
                     correct
                 }
-                None => {
+                FoodSpawn::None => {
                     let correct = 100 - rand.int_n(100) >= usize::from(self.food_chance);
                     if log && !correct {
                         error!("Food spawned, when none should have been spawned");
                     }
                     correct
                 }
+                FoodSpawn::Blocked => {
+                    // We can't get any info if there isn't even a chance for food
+                    true
+                }
             }
         })
     }