Ben Ashton
1 year ago
2 changed files with 144 additions and 0 deletions
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Sensor at x=3556832, y=3209801: closest beacon is at x=3520475, y=3164417 |
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Sensor at x=3068970, y=3071952: closest beacon is at x=3520475, y=3164417 |
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Sensor at x=636397, y=1899889: closest beacon is at x=338784, y=1935796 |
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Sensor at x=3856769, y=3377079: closest beacon is at x=3520475, y=3164417 |
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Sensor at x=2876227, y=2633203: closest beacon is at x=2595700, y=2684432 |
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Sensor at x=1435445, y=1194830: closest beacon is at x=925348, y=2000000 |
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Sensor at x=3764673, y=3881970: closest beacon is at x=3520475, y=3164417 |
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Sensor at x=3171272, y=1098717: closest beacon is at x=3778277, y=740547 |
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Sensor at x=3646837, y=966534: closest beacon is at x=3778277, y=740547 |
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Sensor at x=1736390, y=3309102: closest beacon is at x=1623417, y=4114070 |
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Sensor at x=1086601, y=2272573: closest beacon is at x=925348, y=2000000 |
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Sensor at x=3793954, y=2346914: closest beacon is at x=3520475, y=3164417 |
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Sensor at x=1896054, y=2706210: closest beacon is at x=2595700, y=2684432 |
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Sensor at x=2298950, y=3449308: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=1911518, y=3848874: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=2566355, y=1516144: closest beacon is at x=2595700, y=2684432 |
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Sensor at x=246553, y=343125: closest beacon is at x=338784, y=1935796 |
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Sensor at x=2197183, y=3975039: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=552775, y=3494740: closest beacon is at x=-138318, y=2857049 |
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Sensor at x=128870, y=1935711: closest beacon is at x=338784, y=1935796 |
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Sensor at x=2197078, y=3999879: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=2502533, y=3911039: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=2289309, y=3024440: closest beacon is at x=2595700, y=2684432 |
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Sensor at x=3999523, y=551710: closest beacon is at x=3778277, y=740547 |
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Sensor at x=2246061, y=3999936: closest beacon is at x=2205069, y=3958831 |
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Sensor at x=3982782, y=1306639: closest beacon is at x=3778277, y=740547 |
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Sensor at x=1166660, y=2766482: closest beacon is at x=925348, y=2000000 |
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Sensor at x=3744391, y=440575: closest beacon is at x=3778277, y=740547 |
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Sensor at x=1480453, y=3997346: closest beacon is at x=1623417, y=4114070 |
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Sensor at x=9770, y=1844797: closest beacon is at x=338784, y=1935796 |
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Sensor at x=202829, y=2427690: closest beacon is at x=338784, y=1935796 |
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Sensor at x=3051096, y=3631595: closest beacon is at x=3147080, y=4258152 |
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Sensor at x=2111052, y=297293: closest beacon is at x=1552534, y=-431081 |
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Sensor at x=864326, y=2053355: closest beacon is at x=925348, y=2000000 |
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Sensor at x=2422495, y=2130146: closest beacon is at x=2595700, y=2684432 |
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Sensor at x=3655670, y=100751: closest beacon is at x=3778277, y=740547 |
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Sensor at x=535656, y=2133259: closest beacon is at x=338784, y=1935796 |
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Sensor at x=263229, y=2101270: closest beacon is at x=338784, y=1935796 |
@ -0,0 +1,106 @@ |
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import { readFileSync } from 'node:fs'; |
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const input = readFileSync('input', 'utf-8'); |
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const sensors = input |
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.split('\n') |
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.filter(Boolean) |
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.map(line => { |
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const match = line.match(/.*?x=(-?\d+), y=(-?\d+).*?x=(-?\d+), y=(-?\d+)/); |
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if (!match) { |
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throw new Error(`Invalid sensor readout: ${line}`); |
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} |
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const [x, y, bx, by] = match |
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.slice(1) |
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.map(n => parseInt(n)); |
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return {x, y, bx, by}; |
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}); |
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function rangesOverlap(range1, range2, tollerance=0) { |
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const t = tollerance; |
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range1 = [...range1].sort((a, b) => a - b); |
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range2 = [...range2].sort((a, b) => a - b); |
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return ( |
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(range1[0] >= range2[0] - t && range1[0] <= range2[1] + t) || |
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(range1[1] >= range2[0] - t && range1[1] <= range2[1] + t) || |
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(range2[0] >= range1[0] - t && range2[0] <= range1[1] + t) || |
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(range2[1] >= range1[0] - t && range2[1] <= range1[1] + t) |
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); |
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} |
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function mergeCoverage(coverage) { |
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return [...coverage] |
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.map(range => [...range].sort((a, b) => a - b)) |
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.sort((a, b) => a[0] - b[0]) |
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.reduce((newCoverage, range) => { |
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if (newCoverage.length) { |
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const lastRange = newCoverage[newCoverage.length - 1]; |
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if (rangesOverlap(lastRange, range, 1)) { |
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newCoverage[newCoverage.length - 1] = [ |
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Math.min(lastRange[0], range[0]), |
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Math.max(lastRange[1], range[1]) |
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]; |
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return newCoverage; |
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} |
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} |
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newCoverage.push(range); |
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return newCoverage; |
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}, []); |
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} |
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function getCoverageForRow(y) { |
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const coverage = []; |
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for (const s of sensors) { |
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const range = Math.abs(s.x - s.bx) + Math.abs(s.y - s.by); |
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const distanceToSensor = Math.abs(s.y - y); |
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const reducedRange = range - distanceToSensor; |
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if (reducedRange < 0) continue; |
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coverage.push([s.x - reducedRange, s.x + reducedRange]); |
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} |
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return mergeCoverage(coverage); |
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} |
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function countBeaconsForRow(y) { |
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return sensors |
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.map(s => [s.bx, s.by]) |
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.filter((coord, i, coords) => coords.findLastIndex( |
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c => c[0] === coord[0] && c[1] === coord[1] |
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) === i) |
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.reduce((total, coord) => total + Number(coord[1] === y), 0); |
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} |
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function countCoverageForRow(y) { |
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const coverageCount = getCoverageForRow(y) |
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.reduce((total, range) => total + range[1] - range[0] + 1, 0); |
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const beaconCount = countBeaconsForRow(y); |
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return coverageCount - beaconCount; |
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} |
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const row = 2000000; |
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const coverageCount = countCoverageForRow(2000000); |
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console.log( |
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`There are ${coverageCount} positions that cannot contain a beacon on ` + |
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`row: ${row}` |
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); |
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function limitCoverage(coverage, min, max) { |
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return coverage |
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.filter(range => rangesOverlap([min, max], range)) |
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.map(range => [Math.max(min, range[0]), Math.min(max, range[1])]); |
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} |
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console.log('Locating distress beacon...'); |
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let tuningFrequency; |
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for (let y = 0; y <= 4000000; y++) { |
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const coverage = limitCoverage(getCoverageForRow(y), 0, 4000000); |
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if (coverage.length > 1) { |
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const x = coverage[0][1] + 1; |
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tuningFrequency = x * 4000000 + y; |
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} |
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} |
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console.log(`Tuning frequency for distress beacon: ${tuningFrequency}`); |
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