43 lines
1.4 KiB
TypeScript
43 lines
1.4 KiB
TypeScript
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import {anyCharOf, spaces1, string, whitespace} from "parjs";
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import {between, exactly, manySepBy, stringify, then} from "parjs/combinators";
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import {Range} from "immutable";
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import fs from "fs";
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export type Race = [number, number];
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const timeName = string('Time:').pipe(then(spaces1()));
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const distanceName = string('Distance:').pipe(then(spaces1()));
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const timeParser = anyCharOf("0123456789").pipe(manySepBy(whitespace().pipe(exactly(2))), stringify(), between(timeName, whitespace()));
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const distanceParser = anyCharOf("0123456789").pipe(manySepBy(whitespace().pipe(exactly(2))), stringify(), between(distanceName, whitespace()));
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const parser = timeParser.pipe(then(distanceParser));
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export class BoatRace {
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private readonly race: Race;
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constructor(input: string) {
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const [times, distances] = parser.parse(input).value;
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this.race = [parseInt(times), parseInt(distances)];
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}
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numberOfWinningMethods = (race: Race): number => {
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const [time, distance] = race;
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const canWin = (holdingTime: number) => ((time - holdingTime) * holdingTime) > distance;
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const range = Range(0, time).filter(canWin).cacheResult();
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return range.size || 0;
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}
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public totalNumberOfWaysToBeatRace(): number {
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return this.numberOfWinningMethods(this.race);
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}
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}
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export const runDaySix = () => {
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const input = fs.readFileSync('./inputs/day_six_input.txt', 'utf-8').trimEnd();
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const races = new BoatRace(input);
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console.log(races.totalNumberOfWaysToBeatRace());
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}
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