65 lines
1.8 KiB
JavaScript
65 lines
1.8 KiB
JavaScript
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// Comnbining all ranges (min to max) from each beacon at each level of Y may be fast enough
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const fs = require('fs/promises');
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const sum = (arr) => arr.reduce((total, num) => total+num, 0);
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const arrayOfLength = n => Array.from(Array(n).keys()).map(() => {});
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const parseXY = str => str.match(/x=(.*), y=(.*)$/).slice(1).map(x => parseInt(x));
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const HEIGHT = 4000000;
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const doTouch = (a, b, a2, b2) => {
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const a1 = a - 1;
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const b1 = b + 1;
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if(b1 >= a2 && a1 <= b2) {
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return true;
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}
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return false;
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}
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const getStartEnd = (x, rad) => [x-rad, x+rad];
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const getDistance = (x1, y1, x2, y2) => abs(x1 - x2) + abs(y1 - y2);
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const combineTouching = (a,b,c,d) => {
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return [Math.min(a,c), Math.max(b,d)];
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}
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const abs = x => x < 0 ? x * -1 : x;
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const main = async () => {
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const input = (await fs.readFile("./input.txt", 'utf8')).split("\n").slice(0, -1);
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const sets = input.map(row => row.split(": ").map(parseXY));
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const sensors = sets.map(([[sX, sY], [bX, bY]]) => {
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return [sX, sY, getDistance(sX, sY, bX, bY)];
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});
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for(let row = 0; row <= HEIGHT; row++) {
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const coveredArea = sensors.filter(
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([_, y, rad]) => Math.abs(row-y) <= rad
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).map(
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([x, y, rad]) => getStartEnd(x, rad - Math.abs(row - y))
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).sort(
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(a, b) => a[0] - b[0]
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).reduce((ranges, [a1, b1]) => {
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if(!ranges) {
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return [[a1, b1]];
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}
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const [a, b] = ranges[ranges.length - 1];
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if(doTouch(a, b, a1, b1)){
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ranges[ranges.length - 1] = combineTouching(a, b, a1, b1);
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} else {
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ranges.push([a1, b1]);
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}
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return ranges;
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}, false);
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if(coveredArea.length > 1) {
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console.log("FOUND IT! Answer: ", (coveredArea[0][1] + 1) * 4000000 + row);
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process.exit();
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}
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if(row % 100000 === 0) {
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console.log("DONE: ", row);
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}
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}
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}
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main();
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