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Solution of parallel search for fastest horse from Google interview.
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| export interface Speedy { | |
| speed: number; | |
| } | |
| export class FastestItemsFinder { | |
| constructor( | |
| private readonly config = { | |
| workersCount: 5, | |
| fastestCount: 3, | |
| }, | |
| ) {} | |
| private fastestItems: Speedy[] = []; | |
| async test(items: readonly Speedy[]): Promise<Speedy[]> { | |
| this.fastestItems = []; | |
| const queue = [...items]; | |
| const workers = Array.from({ length: this.config.workersCount }, (_, index) => this.worker(queue, index)); | |
| await Promise.all(workers); | |
| return this.fastestItems; | |
| } | |
| private async worker(queue: Speedy[], index: number) { | |
| console.log(`Worker ${index + 1} started`); | |
| while (queue.length) { | |
| const item = queue.shift(); | |
| console.log(`Worker ${index + 1} is testing item ${item?.speed}`); | |
| if (item) this.testAgainstFastest(item); | |
| // for demonstration purposes only | |
| await new Promise(resolve => setTimeout(resolve, 100)); | |
| } | |
| console.log(`Worker ${index + 1} finished`); | |
| } | |
| private testAgainstFastest(item: Speedy) { | |
| const { fastestCount } = this.config; | |
| for (let i = 0; i < fastestCount; i++) { | |
| const fastestItem = this.fastestItems[i]; | |
| if (!fastestItem || item.speed > fastestItem.speed) { | |
| this.fastestItems.splice(i, 0, item); | |
| this.fastestItems = this.fastestItems.slice(0, fastestCount); | |
| break; | |
| } | |
| } | |
| } | |
| } | |
| new FastestItemsFinder() | |
| .test([ | |
| { speed: 8 }, | |
| { speed: 1 }, | |
| { speed: 3 }, | |
| { speed: 4 }, | |
| { speed: 9 }, | |
| { speed: 5 }, | |
| { speed: 2 }, | |
| { speed: 10 }, | |
| { speed: 7 }, | |
| { speed: 6 }, | |
| ]) | |
| .then(fastestHorses => { | |
| fastestHorses.forEach((horse, index) => { | |
| console.log(`Fastest ${index + 1}. horse has speed ${horse.speed}`); | |
| }); | |
| console.log('Done!'); | |
| }) | |
| .catch(console.error); |
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