95 lines
2.4 KiB
JavaScript
95 lines
2.4 KiB
JavaScript
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import fs from "fs";
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const EMPTY = "L";
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const OCCUPIED = "#";
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const FLOOR = ".";
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class Field {
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/**
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* @param {string[][]} lines Lines of the field
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*/
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constructor(lines) {
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this.lines = lines;
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}
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toString() {
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return this.lines.map((line) => line.join("")).join("\n");
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}
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get occupiedSeatCount() {
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return this.lines.reduce(
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(result, line) => result + line.filter((val) => val === OCCUPIED).length,
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0
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);
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}
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/**
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* Checks visible seats from a given position
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*
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* @param {number} x X-Coordinate of the seat to check
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* @param {number} y Y-Coordinate of the seat to check
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* @returns {Promise<number>} Amount of seats visible from the given position
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*/
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checkVisibleSeats(x, y) {
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let occupiedNeighbors = 0;
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for (let dY = -1; dY <= 1; dY++) {
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const curLine = this.lines[y + dY];
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if (curLine === undefined) continue;
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for (let dX = -1; dX <= 1; dX++) {
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if (dX === 0 && dY === 0) continue;
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const curCell = curLine[x + dX];
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if (curCell === OCCUPIED) occupiedNeighbors++;
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}
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}
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return occupiedNeighbors;
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}
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/**
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* @returns {number} Amount of seats that changed states.
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*/
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step() {
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let changes = 0;
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/** @type {string[][]} */
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const changedLines = JSON.parse(JSON.stringify(this.lines));
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for (let y = 0; y < this.lines.length; y++) {
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for (let x = 0; x < this.lines[y].length; x++) {
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const currentCell = this.lines[y][x];
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if (currentCell === FLOOR) continue;
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const occupiedNeighbors = this.checkVisibleSeats(x, y);
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if (currentCell === EMPTY && occupiedNeighbors === 0) {
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changedLines[y][x] = OCCUPIED;
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changes++;
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} else if (currentCell === OCCUPIED && occupiedNeighbors >= 4) {
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changedLines[y][x] = EMPTY;
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changes++;
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}
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}
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}
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this.lines = changedLines;
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return changes;
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}
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}
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/**
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* Main function for Puzzle A
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*
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* @param {string} data - Puzzle input as a single string.
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* @returns {number} Amount of open seats after applying all rules until stable.
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*/
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async function main(data) {
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const lines = data.split(/\r?\n/).map((line) => line.split(""));
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const field = new Field(lines);
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let steps = 0;
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while (field.step() > 0) {
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// console.log("Step", ++steps);
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}
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return field.occupiedSeatCount;
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}
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fs.readFile("input", (err, data) => {
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if (err) throw err;
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main(data.toString()).then(console.log).catch(console.error);
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});
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