Day Seven Part One, Start Part Two

index.ts

@@ -1,2 +1,3 @@
-import {runDaySix} from "./src/day_six";
-runDaySix()
+import {runDaySeven} from "./src/day_seven";
+
+runDaySeven();

src/day_seven.test.ts

@@ -0,0 +1,37 @@
+import {CamelCard, CamelCards} from "./day_seven";
+
+describe('Day Seven', () => {
+	const input = `32T3K 765
+T55J5 684
+KK677 28
+KTJJT 220
+QQQJA 483`;
+
+	it.each([
+		['AAAAA', 7], // Five of a kind
+		['AA8AA', 6], // Four of a kind
+		['AABBB', 5], //  Full house
+		['T55C5', 4], // Three of a kind
+		['KK677', 3], // Two pairs
+		['32T3K', 2], // One pair
+		['12345', 1], // High card
+
+		['T55J5', 6], // Four of a kind with Joker
+		['KTJJT', 6],
+		['QQQJA', 6]
+	])('should should correctly score %s as %s', (card, score) => {
+		const camelCard = new CamelCard(card);
+		expect(camelCard.score).toEqual(score);
+	});
+
+	it('should correctly compare two clashing cards', () => {
+		const a = new CamelCard('AA2CC');
+		const b = new CamelCard('AATCC');
+		expect(a.compare(b)).toBeLessThan(0);
+	});
+
+	it('should parse the input and calculate the total winnings', () => {
+		const camelCards = new CamelCards(input);
+		expect(camelCards.winnings).toEqual(5905);
+	})
+});

src/day_seven.ts

@@ -0,0 +1,78 @@
+import {isEqual, zip} from "lodash";
+import {anyChar, int, newline, rest, space, whitespace} from "parjs";
+import {stringify, manyBetween, between, then, manySepBy, manyTill} from "parjs/combinators";
+import fs from "fs";
+
+const CardLetterScores = ['J', '2', '3', '4', '5', '6', '7', '8', '9', 'T', 'Q', 'K', 'A'];
+
+export class CamelCard {
+	private readonly hand: Record<string, number>;
+	public readonly score: number;
+
+	constructor(protected readonly card: string) {
+		this.hand = this.card.split('').reduce((cards, char) => {
+			if (!cards[char]) {
+				cards[char] = 0;
+			}
+
+			cards[char] += 1;
+			return cards;
+		}, {} as Record<string, number>)
+
+		this.score = this.calculateScore();
+	}
+
+	public compare(other: CamelCard): number {
+		const diff = this.score - other.score;
+		if (diff !== 0) return diff;
+
+		for (const [a, b] of zip(this.card.split(''), other.card.split('')) as [string, string][]) {
+			if (a !== b) {
+				return CardLetterScores.indexOf(a) - CardLetterScores.indexOf(b)
+			}
+		}
+
+		return 0;
+	}
+
+	private calculateScore(): number {
+		const cards = Object.values(this.hand).sort((a, b) => b-a);
+
+		if (isEqual(cards, [1, 1, 1, 1, 1])) return 1;
+		if (isEqual(cards, [2, 1, 1, 1])) return 2;
+		if (isEqual(cards, [2, 2, 1])) return 3;
+		if (isEqual(cards, [3, 1, 1])) return 4;
+		if (isEqual(cards, [3, 2])) return 5;
+		if (isEqual(cards, [4, 1])) return 6;
+		if (isEqual(cards, [5])) return 7;
+
+		return 0;
+	}
+}
+
+const cardParser = anyChar().pipe(manyTill(space()), stringify());
+const bidParser = int().pipe(between(whitespace()));
+const parser = cardParser.pipe(then(bidParser), manySepBy(whitespace()));
+
+export class CamelCards {
+	private cards: [CamelCard, number][] = [];
+
+	constructor(input: string) {
+		const pairs = parser.parse(input).value;
+
+		this.cards = pairs.map(([cards, bid]) => [new CamelCard(cards), bid]);
+	}
+
+	get winnings(): number {
+		this.cards.sort(([a], [b]) => a.compare(b));
+
+		return this.cards.reduce((total, [_, value], index) => total + (value * (index + 1)), 0);
+	}
+}
+
+export const runDaySeven = () => {
+	const input = fs.readFileSync('./inputs/day_seven_input.txt', 'utf-8').trimEnd();
+
+	const cards = new CamelCards(input);
+	console.log(cards.winnings);
+}