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import fs from "fs";
const input = fs.readFileSync("./input.txt").toString();
const [seedStr, ...mapStrings] = input.split("\n\n");
export function chunks<T>(data: Array<T>, chunkSize: number) {
return data.reduce((acc, value, index) => {
// Initialize a new chunk
if (index % chunkSize === 0) acc.push([]);
acc[acc.length - 1].push(value);
return acc;
}, [] as T[][]);
}
const seedRanges = chunks(seedStr.match(/\d+/g)?.map(Number) || [], 2).map(
([start, size]) => {
return { start, size };
},
);
const maps = mapStrings.map((mapString) =>
mapString
.split("\n")
.slice(1)
.filter((x) => x.length)
.map((s) => s.match(/\d+/g)?.map(Number) || [])
.map(([destinationStart, sourceStart, rangeSize]) => ({
sourceStart,
destinationStart,
rangeSize,
})),
);
// We dont need to inspect whole seed ranges, instead we only select "interesting points"
// Interesting points lie at starts/end of ranges defined in our maps
const seeds = maps
.flatMap((ranges) =>
ranges.flatMap((r) => [r.sourceStart, r.destinationStart + 1]),
)
.filter((breakpoint) =>
seedRanges.find(
(range) =>
breakpoint >= range.start && breakpoint < range.start + range.size,
),
);
const locationNumbers = seeds.map((seed) =>
maps.reduce((currentNumber, mapRules) => {
const validRule = mapRules.find(
(rule) =>
currentNumber >= rule.sourceStart &&
currentNumber < rule.sourceStart + rule.rangeSize,
);
if (!validRule) return currentNumber;
return currentNumber - validRule.sourceStart + validRule.destinationStart;
}, seed),
);
const result = locationNumbers.reduce((acc, x) => Math.min(acc, x), Infinity);
console.log({ result });
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