.

Author: Platane

cargo/snk-solver/src/snake_path.rs

@@ -55,6 +55,10 @@ impl PartialOrd for Node {
     }
 }
 
+// move a snake from a position to a point (that it reaches with its head)
+//
+// it should be the same as path finding from cell to cell
+// with the caveat that is might block it-self in the first N step (for a snake of size N)
 pub fn get_snake_path(
     grid: &Grid<Color>,
     from: &Snake4,
@@ -80,10 +84,7 @@ pub fn get_snake_path(
 
     while let Some(node) = open_list.pop() {
         loop_count += 1;
-
-        if loop_count > 20_000 {
-            panic!("loop_count out of control")
-        }
+        debug_assert!(loop_count < 20_000, "invariant: loop out of control");
 
         let node_cost = node.cost;
 

cargo/snk-solver/src/solver.rs

@@ -137,6 +137,17 @@ pub fn solve(color_grid: &Grid<Color>, snake: &Snake4) -> Vec<Direction> {
                 })
                 .collect();
         }
+
+        debug_assert!(
+            iter_rectangle_fill(color_grid.width, color_grid.height)
+                .filter(|p| {
+                    let color = color_grid.get_color(*p);
+                    color.is_empty() || color >= color
+                })
+                .next()
+                .is_none(),
+            "invariant: should have cleared the color"
+        )
     }
 
     path