From 6f895c334103e4279af32062ff359aec944f120a Mon Sep 17 00:00:00 2001
From: Tim Kurvers <tim@moonsphere.net>
Date: Sat, 21 Dec 2024 19:00:35 +0100
Subject: [PATCH] feat(js): add solutions for 2024 day 19

---
 js/src/2024/19/index.js       | 48 +++++++++++++++++++++++++++++++++++
 puzzles/2024/19/examples.yaml | 17 +++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 js/src/2024/19/index.js
 create mode 100644 puzzles/2024/19/examples.yaml

diff --git a/js/src/2024/19/index.js b/js/src/2024/19/index.js
new file mode 100644
index 0000000..861ac38
--- /dev/null
+++ b/js/src/2024/19/index.js
@@ -0,0 +1,48 @@
+import { solution } from '../../utils/index.js';
+
+const parse = (input) => {
+  const parts = input.trim().split('\n\n');
+
+  const available = parts[0].split(', ');
+  const desired = parts[1].split('\n');
+
+  return { available, desired };
+};
+
+// Calculates whether a given design is possible and returns how many variations
+const build = (design, available, cache = new Map()) => {
+  if (cache.has(design)) {
+    return cache.get(design);
+  }
+
+  let count = 0;
+  for (const pattern of available) {
+    if (design.startsWith(pattern)) {
+      const remaining = design.slice(pattern.length);
+
+      if (!remaining.length) {
+        count += 1;
+        continue;
+      }
+
+      count += build(remaining, available, cache);
+    }
+  }
+  cache.set(design, count);
+  return count;
+};
+
+export const partOne = solution((input) => {
+  const { available, desired } = parse(input);
+  return desired.reduce((sum, design) => {
+    if (build(design, available)) {
+      return sum + 1;
+    }
+    return sum;
+  }, 0);
+});
+
+export const partTwo = solution((input) => {
+  const { available, desired } = parse(input);
+  return desired.reduce((sum, design) => sum + build(design, available), 0);
+});
diff --git a/puzzles/2024/19/examples.yaml b/puzzles/2024/19/examples.yaml
new file mode 100644
index 0000000..abedfdd
--- /dev/null
+++ b/puzzles/2024/19/examples.yaml
@@ -0,0 +1,17 @@
+part-one:
+  - input: &example1 |
+      r, wr, b, g, bwu, rb, gb, br
+
+      brwrr
+      bggr
+      gbbr
+      rrbgbr
+      ubwu
+      bwurrg
+      brgr
+      bbrgwb
+    answer: 6
+
+part-two:
+  - input: *example1
+    answer: 16