33 lines
787 B
JavaScript
33 lines
787 B
JavaScript
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import { readFileSync } from 'node:fs';
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const input = readFileSync('input', 'utf-8');
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function isValidMarker(marker) {
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return marker.split('').every((c, i, word) => word.lastIndexOf(c) === i);
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}
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function findMarker(markerLength) {
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for (let pos = markerLength; pos <= input.length; pos++) {
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const marker = input.slice(pos - markerLength, pos);
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if (isValidMarker(marker)) {
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return { marker, pos };
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}
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}
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}
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const packetMarker = findMarker(4);
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if (packetMarker) {
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console.log(
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`Found packet marker: ${packetMarker.marker} after: ${packetMarker.pos} ` +
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`characters`
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);
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}
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const messageMarker = findMarker(14);
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if (messageMarker) {
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console.log(
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`Found message marker: ${messageMarker.marker} after: ` +
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`${messageMarker.pos} characters`
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);
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}
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