2023 - Day 4

2023/04/solution.ts

@@ -0,0 +1,41 @@
+const sample = await Deno.readTextFile("sample.txt");
+const input = await Deno.readTextFile("input.txt");
+
+const solvePart1 = (data: string): number =>
+  data.split("\n").filter(Boolean).map((line) =>
+    line.split(/:\ +/)[1]?.split(/\ +\|\ +/).map((parts) =>
+      parts.split(/\ +/).map(Number)
+    )
+  )
+    .map(([winning, yours]) => yours.filter((n) => winning.includes(n)))
+    .map((matches) => matches.reduce((a, _, i) => i === 0 ? 1 : a * 2, 0))
+    .reduce((s, v) => s + v, 0);
+
+console.log("Sample:", solvePart1(sample)); // 13
+console.log("Input", solvePart1(input)); // 22488
+
+const solvePart2 = (data: string): number => {
+  const x = data
+    .split("\n")
+    .filter(Boolean)
+    .map((line) =>
+      line
+        .split(/:\ +/)[1]
+        ?.split(/\ +\|\ +/)
+        .map((parts) => parts.split(/\ +/).map(Number))
+    )
+    .map(([winning, yours]) => yours.filter((n) => winning.includes(n)))
+    .map((matches, index) => [index + 1, matches.length])
+    .reduce((r, [i, l]) => {
+      r[i] = r[i] || 1
+      for (let j = i + 1; j < i + l + 1; j += 1) {
+        r[j] = (r[j] ?? 1) + (1 * (r[i] ?? 1));
+      }
+      return r;
+    }, { "1": 1 } as Record<number, number>);
+
+  return Object.values(x).reduce((s, v) => s + v);
+};
+
+console.log("Sample2:", solvePart2(sample)); // 30
+console.log("Input", solvePart2(input)); // 7013204