feat(day04): Part 1

Author: coderbyheart

day04_test.ts

@@ -0,0 +1,93 @@
+import { assertEquals } from "https://deno.land/std@0.208.0/assert/assert_equals.ts";
+import { sum } from "./util/sum.ts";
+
+const card1 = `Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53`;
+const card2 = `Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19`;
+const card3 = `Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1`;
+const card4 = `Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83`;
+const card5 = `Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36`;
+const card6 = `Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11`;
+
+Deno.test("Day 4: Scratchcards", async (t) => {
+  await t.step("Part 1", async (t) => {
+    await t.step("Example", async (t) => {
+      for (const [card, expectedWinningNumbers, expectedPoints] of [
+        [card1, [48, 83, 17, 86], 8],
+        [card2, [32, 61], 2],
+        [card3, [1, 21], 2],
+        [card4, [84], 1],
+        [card5, [], 0],
+        [card6, [], 0],
+      ] as [string, Array<number>, number][]) {
+        await t.step(
+          `card ${card} should have the winning numbers ${expectedWinningNumbers}`,
+          () =>
+            assertEquals(winningNumbers(card), new Set(expectedWinningNumbers))
+        );
+
+        await t.step(`card ${card} should score ${expectedPoints} points`, () =>
+          assertEquals(cardScore(card), expectedPoints)
+        );
+      }
+
+      await t.step("Sum of pile", () =>
+        assertEquals(
+          sum([card1, card2, card3, card4, card5, card6].map(cardScore)),
+          13
+        )
+      );
+    });
+
+    await t.step("Solution", async () =>
+      assertEquals(
+        sum(
+          (await Deno.readTextFile("./input/day04.txt"))
+            .split("\n")
+            .map(cardScore)
+        ),
+        28538
+      )
+    );
+  });
+
+  await t.step("parseCard()", () =>
+    assertEquals(parseCard(card3), [
+      new Set([1, 21, 53, 59, 44]),
+      new Set([69, 82, 63, 72, 16, 21, 14, 1]),
+    ])
+  );
+});
+
+const winningNumbers = (cardInfo: string): Set<number> => {
+  const [winningNumbers, cardNumbers] = parseCard(cardInfo);
+  const winners = new Set<number>();
+  for (const number of cardNumbers.values()) {
+    if (winningNumbers.has(number)) winners.add(number);
+  }
+  return winners;
+};
+const cardScore = (cardInfo: string): number =>
+  winningNumbers(cardInfo).size === 0
+    ? 0
+    : (1 * Math.pow(2, winningNumbers(cardInfo).size)) / 2;
+
+const parseCard = (cardInfo: string): [Set<number>, Set<number>] => {
+  const [, winningNumbers, cardNumbers] =
+    /^Card +\d+: ([\d ]+)+ \| ([\d ]+)+/.exec(cardInfo) ?? [];
+  return [
+    new Set(
+      winningNumbers
+        .trim()
+        .replace(/ +/g, " ")
+        .split(" ")
+        .map((s) => parseInt(s, 10))
+    ),
+    new Set(
+      cardNumbers
+        .trim()
+        .replace(/ +/g, " ")
+        .split(" ")
+        .map((s) => parseInt(s, 10))
+    ),
+  ];
+};