expeditaet/solutions/typescript/2021/10/src/p1.ts

Advent of Code Solutions

import { isNotNullish, task } from '@alexaegis/advent-of-code-lib';
import packageJson from '../package.json';
import { closingTagMap, isOpeningTag, type ClosingTag, type OpeningTag } from './model/index.js';

const scoreMap: Record<ClosingTag, number> = {
	')': 3,
	']': 57,
	'}': 1197,
	'>': 25_137,
};

export const getFirstCorruptTag = (line: string): ClosingTag | undefined => {
	const chars = [...line] as (OpeningTag | ClosingTag)[];
	const openStack: OpeningTag[] = [];
	for (const char of chars) {
		if (isOpeningTag(char)) {
			openStack.push(char);
		} else {
			const lastOpeningTag = openStack.pop();
			if (lastOpeningTag && char !== closingTagMap[lastOpeningTag]) {
				return char;
			}
		}
	}
	return undefined;
};

export const p1 = (input: string): number =>
	input
		.lines()
		.map(getFirstCorruptTag)
		.filter(isNotNullish)
		.map((closingTag) => scoreMap[closingTag])
		.sum();

await task(p1, packageJson.aoc); // 193275 ~0.27ms