Day 8

day8.peggy

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+lines = (@[^\n]+ "\n")*

day8.ts

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+import { Point, Rect } from './lib/rect.ts';
+import { Sequence } from './lib/sequence.ts';
+import { type MainArgs, parseFile } from './lib/utils.ts';
+
+type Parsed = string[][];
+
+class Field extends Rect {
+  antennae = new Map<string, Point[]>();
+  nodes: Point[] = [];
+
+  constructor(inp: Parsed, self = false) {
+    super(inp);
+    this.forEach((v, x, y) => {
+      if (v === '.') {
+        return;
+      }
+      let m = this.antennae.get(v);
+      if (!m) {
+        m = [];
+        this.antennae.set(v, m);
+      }
+      const p = new Point(x, y);
+      m.push(p);
+      if (self) {
+        this.nodes.push(p);
+      }
+    });
+  }
+
+  push(p: Point): boolean {
+    if (!this.check(p)) {
+      return false;
+    }
+    this.nodes.push(p);
+    return true;
+  }
+
+  count(): number {
+    const locs = new Set<string>();
+    for (const p of this.nodes) {
+      if (this.check(p)) {
+        locs.add(p.toString());
+      }
+    }
+    return locs.size;
+  }
+}
+
+function part1(inp: Parsed): number {
+  const r = new Field(inp);
+
+  for (const [_k, v] of r.antennae) {
+    for (const [a, b] of new Sequence(v).combinations(2)) {
+      const dx = a.x - b.x;
+      const dy = a.y - b.y;
+      r.push(a.xlate(dx, dy));
+      r.push(b.xlate(-dx, -dy));
+    }
+  }
+
+  return r.count();
+}
+
+function part2(inp: Parsed): number {
+  const r = new Field(inp, true);
+
+  for (const [_k, v] of r.antennae) {
+    for (const [a, b] of new Sequence(v).combinations(2)) {
+      const dx = a.x - b.x;
+      const dy = a.y - b.y;
+      let p = a.xlate(dx, dy);
+      while (r.push(p)) {
+        p = p.xlate(dx, dy);
+      }
+      p = b.xlate(-dx, -dy);
+      while (r.push(p)) {
+        p = p.xlate(-dx, -dy);
+      }
+    }
+  }
+  return r.count();
+}
+
+export default async function main(args: MainArgs): Promise<[number, number]> {
+  const inp = await parseFile<Parsed>(args);
+  return [part1(inp), part2(inp)];
+}

test/day8.js

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+export default [240, 955];