Finally do Day Five

src/day_five.test.ts

@@ -0,0 +1,42 @@
+import {mapSeedToLocation} from "./day_five";
+
+describe('Day Five', () => {
+	const input = `seeds: 79 14 55 13
+
+seed-to-soil map:
+50 98 2
+52 50 48
+
+soil-to-fertilizer map:
+0 15 37
+37 52 2
+39 0 15
+
+fertilizer-to-water map:
+49 53 8
+0 11 42
+42 0 7
+57 7 4
+
+water-to-light map:
+88 18 7
+18 25 70
+
+light-to-temperature map:
+45 77 23
+81 45 19
+68 64 13
+
+temperature-to-humidity map:
+0 69 1
+1 0 69
+
+humidity-to-location map:
+60 56 37
+56 93 4`;
+
+	it('should calculate the smallest location from the input', () => {
+		const result = mapSeedToLocation(input);
+		expect(result).toEqual(46);
+	});
+});

src/day_five.ts

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+import {Range, Seq} from "immutable";
+import {chunk} from "lodash";
+import fs from "fs";
+
+type MapRange = {
+	source: number;
+	destination: number;
+	size: number;
+}
+
+const parseSeeds = (input: string): Seq.Indexed<number> => {
+	const [_, seedString] = input.split('seeds: ');
+
+	return chunk(seedString.split(' '), 2).reduce((seeds, [start, size]) => {
+		return seeds.concat(Range(Number(start), Number(start) + Number(size)));
+	}, Seq.Indexed<number>());
+}
+
+const mapMapper = (input: string): MapRange[] => {
+	const [_, ...lines] = input.split('\n');
+
+	return lines.map(line => {
+		const [dest, source, size] = line.split(' ').map(Number);
+		return {
+			source: source,
+			destination: dest,
+			size
+		}
+	});
+}
+
+const seedMapper = (seed: number, map: MapRange[]): number => {
+	const mapped = map.find(({source, destination, size}) => {
+		return seed >= source && seed < source + size;
+	});
+
+	if (!mapped) {
+		return seed;
+	}
+
+	return seed - mapped.source + mapped.destination;
+}
+
+export const mapSeedToLocation = (input: string): number => {
+	const [seedsStr, ...mapStrings] = input.split('\n\n');
+	const seeds = parseSeeds(seedsStr);
+
+	const maps = mapStrings.map(mapMapper);
+
+	const mapped = seeds.map(seed => {
+		return maps.reduce((seed, map) => seedMapper(seed, map), seed);
+	});
+
+	return mapped.min()!;
+}
+
+export const runDayFive = () => {
+	const input = fs.readFileSync('./inputs/day_five_input.txt', 'utf8').trimEnd();
+	const result = mapSeedToLocation(input);
+	console.log(`Day Five: ${result}`);
+}