71 lines
1.8 KiB
TypeScript
71 lines
1.8 KiB
TypeScript
import { combinations, unique } from '../../utils/array.ts';
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import {
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type Coordinates,
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inBounds,
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isCoordinateEqual
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} from '../../utils/coordinates.ts';
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export function groupCoordinates(rows: string[]) {
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const antennas = new Map<string, Coordinates>();
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for (let y = 0; y < rows.length; y++) {
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for (let x = 0; x < rows[y].length; x++) {
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const char = rows[y][x];
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if (char === '.') {
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continue;
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}
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const entry = antennas.get(char) || [];
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entry.push([x, y]);
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antennas.set(char, entry);
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}
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}
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return antennas;
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}
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export function solveFirst(input: string): number {
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const rows = input.split('\n');
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const antennas = groupCoordinates(rows);
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const antiNodes: Coordinates = [];
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antennas.forEach((positions) => {
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combinations(positions).forEach(({ a, b }) =>
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antiNodes.push([a[0] - (b[0] - a[0]), a[1] - (b[1] - a[1])])
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);
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});
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const validAntiNodes = antiNodes
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.filter(inBounds(rows[0].length, rows.length))
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.filter(unique(isCoordinateEqual));
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return validAntiNodes.length;
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}
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export function solveSecond(input: string): number {
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const rows = input.split('\n');
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const antennas = groupCoordinates(rows);
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const antiNodes: Coordinates = [];
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antennas.forEach((positions) => {
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combinations(positions).forEach(({ a, b }) => {
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for (let y = 0; y < rows.length; y++) {
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antiNodes.push([a[0] + (b[0] - a[0]) * y, a[1] + (b[1] - a[1]) * y]);
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}
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});
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});
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const validAntiNodes = antiNodes
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.filter(inBounds(rows[0].length, rows.length))
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.filter(unique(isCoordinateEqual));
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// Show the anti-nodes on the input map
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//
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// validAntiNodes.forEach(
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// ([x, y]) => rows[y][x] === '.' && replaceChar(rows, x, y, '#')
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// );
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//
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// console.log(rows.join('\n'));
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return validAntiNodes.length;
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}
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