feat: 2024 Day 13

Author: mfulton26

2024/day/13/part/1/solve.test.ts

@@ -0,0 +1,24 @@
+import solve from "./solve.ts";
+
+import { assertEquals } from "../../../../../lib/testing/asserts.ts";
+
+Deno.test("example", () => {
+  const input = `\
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279`;
+
+  assertEquals(solve(input), 480);
+});

2024/day/13/part/1/solve.ts

@@ -0,0 +1,20 @@
+const regExp =
+  /^Button A: X\+(?<ax>\d+), Y\+(?<ay>\d+)$\n^Button B: X\+(?<bx>\d+), Y\+(?<by>\d+)$\n^Prize: X=(?<px>\d+), Y=(?<py>\d+)$/gm;
+
+export default function solve(input: string) {
+  const configs = input.matchAll(regExp).map((array) => array.map(Number))
+    .map(([, ax, ay, bx, by, px, py]) => ({ ax, ay, bx, by, px, py }))
+    .toArray();
+  let tokens = 0;
+  for (const { ax, ay, bx, by, px, py } of configs) {
+    let minTokens = Infinity;
+    for (let a = 0; a < 100; a++) {
+      for (let b = 0; b < 100; b++) {
+        const x = a * ax + b * bx, y = a * ay + b * by, $ = 3 * a + b;
+        if (x === px && y === py && $ < minTokens) minTokens = $;
+      }
+    }
+    if (minTokens !== Infinity) tokens += minTokens;
+  }
+  return tokens;
+}

2024/day/13/part/2/solve.test.ts

@@ -0,0 +1,24 @@
+import solve from "./solve.ts";
+
+import { assertEquals } from "../../../../../lib/testing/asserts.ts";
+
+Deno.test("example", () => {
+  const input = `\
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279`;
+
+  assertEquals(solve(input, { offset: 0 }), 480);
+});

2024/day/13/part/2/solve.ts

@@ -0,0 +1,16 @@
+const regExp =
+  /^Button A: X\+(?<ax>\d+), Y\+(?<ay>\d+)$\n^Button B: X\+(?<bx>\d+), Y\+(?<by>\d+)$\n^Prize: X=(?<px>\d+), Y=(?<py>\d+)$/gm;
+
+export default function solve(input: string, { offset = 10000000000000 } = {}) {
+  const configs = input.matchAll(regExp).map((array) => array.map(Number))
+    .map(([, ax, ay, bx, by, px, py]) => ({ ax, ay, bx, by, px, py }))
+    .toArray();
+  for (const config of configs) config.px += offset, config.py += offset;
+  let tokens = 0;
+  for (const { ax, ay, bx, by, px, py } of configs) {
+    const d = ax * by - bx * ay;
+    const at = (px * by - py * bx) / d, bt = (py * ax - px * ay) / d;
+    if (Number.isInteger(at) && Number.isInteger(bt)) tokens += 3 * at + bt;
+  }
+  return tokens;
+}