some extra utils

utils/index.ts

@@ -1,2 +1,3 @@
 export * from "./jsonds";
 export * from "./point2d";
+export * from "./str";

utils/point2d.ts

@@ -7,3 +7,25 @@ export const l2Norm = (p1: Vec2, p2: Vec2) =>
   Math.sqrt(Math.pow(p2.x - p1.x, 2) + Math.pow(p2.y - p1.y, 2));
 
 export const isDiagAdj = (p1: Vec2, p2: Vec2) => l2Norm(p1, p2) <= Math.sqrt(2);
+
+export const neighbors = (p1: Vec2, max: Vec2) => {
+  const ns: Vec2[] = [];
+  const { x, y } = p1;
+  for (let dy = -1; dy <= 1; dy++) {
+    for (let dx = -1; dx <= 1; dx++) {
+      const [newX, newY] = [dx + x, dy + y];
+      if (
+        !(dy === dx && dy === 0) &&
+        newX >= 0 &&
+        newX < max.x &&
+        newY < max.y &&
+        newY >= 0
+      ) {
+        ns.push({ x: newX, y: newY });
+      }
+    }
+  }
+  return ns;
+};
+
+export const;

utils/str.ts

@@ -0,0 +1 @@
+export const isNumeric = (symbol: string) => symbol <= "9" && symbol >= "0";