🚀 prune layer algorithm

packages/demo/demo.pruneLayer.ts

@@ -0,0 +1,48 @@
+import { createCanvas } from "./canvas";
+import { Color, copyGrid } from "../compute/grid";
+import { grid, snake } from "./sample";
+import { pruneLayer } from "@snk/compute/getBestRoute-layer";
+
+const colors = [1, 2, 3] as Color[];
+
+const snakeN = snake.length / 2;
+
+const layers = [{ grid, chunk: [] as { x: number; y: number }[] }];
+let grid0 = copyGrid(grid);
+for (const color of colors) {
+  const chunk = pruneLayer(grid0, color, snakeN);
+  layers.push({ chunk, grid: copyGrid(grid0) });
+}
+
+const { canvas, ctx, draw } = createCanvas(grid);
+document.body.appendChild(canvas);
+
+let k = 0;
+
+const loop = () => {
+  const { grid, chunk } = layers[k];
+
+  draw(grid, snake, []);
+
+  ctx.fillStyle = "orange";
+  chunk.forEach(({ x, y }) => {
+    ctx.beginPath();
+    ctx.fillRect((1 + x + 0.5) * 16 - 2, (2 + y + 0.5) * 16 - 2, 4, 4);
+  });
+};
+
+loop();
+
+const input = document.createElement("input") as any;
+input.type = "range";
+input.value = 0;
+input.step = 1;
+input.min = 0;
+input.max = layers.length - 1;
+input.style.width = "90%";
+input.addEventListener("input", () => {
+  k = +input.value;
+  loop();
+});
+document.body.append(input);
+document.body.addEventListener("click", () => input.focus());