Initial Commit

2023/02/index.ts

@@ -0,0 +1,45 @@
+import { groupBy, multBy, sumArray, sumBy } from '../../utils/array.ts';
+
+export type AllowedCubes = Record<string, number>;
+
+function parseInput(input: string) {
+  const matchLine = input.matchAll(/^Game (\d*): (.*)$/gm);
+
+  return Array.from(matchLine, (m) => ({
+    id: Number(m[1]),
+    rounds: m[2].split('; ').map((r) =>
+      r.split(', ').map((g) => {
+        const [amount, color] = g.split(' ');
+        return { color, amount: Number(amount) };
+      })
+    )
+  }));
+}
+
+export function solveFirst(input: string, allowed: AllowedCubes): number {
+  const games = parseInput(input);
+
+  const possible = games.filter(
+    (g) =>
+      !g.rounds.some((r) =>
+        r.some((s) => !(s.color in allowed) || s.amount > allowed[s.color])
+      )
+  );
+
+  return sumBy(possible, (a) => a.id);
+}
+
+export function solveSecond(input: string): number {
+  const games = parseInput(input);
+
+  const leastCubes = games.map((g) =>
+    groupBy(g.rounds.flat(), (e) => e.color).map(({ key, elements }) => ({
+      key,
+      amount: elements.toSorted((a, b) => b.amount - a.amount)[0].amount
+    }))
+  );
+
+  const powers = leastCubes.map((cubes) => multBy(cubes, (c) => c.amount));
+
+  return sumArray(powers);
+}