🚀 improve clean layer

packages/compute/cleanLayer-monobranch.ts

@@ -0,0 +1,59 @@
+/**
+ * clean layer is too expensive with solution branching
+ * do not branch for faster result ( at the cost of finding a minimal step number )
+ */
+
+import { copyGrid, setColorEmpty } from "@snk/types/grid";
+import { getHeadX, getHeadY } from "@snk/types/snake";
+import { getAvailableRoutes } from "./getAvailableRoutes";
+import type { Snake } from "@snk/types/snake";
+import type { Grid } from "@snk/types/grid";
+import type { Point } from "@snk/types/point";
+
+export const getAvailableWhiteListedRoute = (
+  grid: Grid,
+  snake: Snake,
+  whiteList: Point[]
+) => {
+  let solution: Snake[] | null;
+
+  getAvailableRoutes(grid, snake, (chain) => {
+    const hx = getHeadX(chain[0]);
+    const hy = getHeadY(chain[0]);
+
+    if (!whiteList.some(({ x, y }) => hx === x && hy === y)) return false;
+
+    solution = chain;
+
+    return true;
+  });
+
+  // @ts-ignore
+  return solution;
+};
+
+export const cleanLayer = (grid0: Grid, snake0: Snake, chunk0: Point[]) => {
+  const chunk = chunk0.slice();
+  const grid = copyGrid(grid0);
+  let snake = snake0;
+  const chain: Snake[] = [];
+
+  while (chunk.length) {
+    const chainN = getAvailableWhiteListedRoute(grid, snake, chunk);
+
+    if (!chainN) throw new Error("some cells are unreachable");
+
+    chain.unshift(...chainN);
+    snake = chain[0];
+
+    const x = getHeadX(snake);
+    const y = getHeadY(snake);
+
+    setColorEmpty(grid, x, y);
+
+    const i = chunk.findIndex((c) => c.x === x && c.y === y);
+    chunk.splice(i, 1);
+  }
+
+  return chain;
+};