73 lines
2.4 KiB
JavaScript
73 lines
2.4 KiB
JavaScript
import fs from 'node:fs'
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let map = []
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function init(filename) {
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const data = fs.readFileSync(filename, { encoding: 'utf-8' }, data => data)
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map = data.split('\n')
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const guard = new Guard()
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guard.position = guard.find()
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console.log(`guard is at ${guard.position}`)
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guard.solve1()
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}
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class Guard {
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constructor() {
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this.position = [0, 0]
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this.visited = []
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this.dir = [-1, 0] // y, x - looking up
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this.steps = 0
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}
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rotate() {
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const [y, x] = this.dir
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if (y === -1 && x === 0) { console.log(`going right`); this.dir = [0, 1] }
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if (y === 0 && x === 1) { console.log(`going down`); this.dir = [1, 0] }
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if (y === 1 && x === 0) { console.log(`going left`); this.dir = [0, -1] }
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if (y === 0 && x === -1) { console.log(`going up`); this.dir = [-1, 0] }
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return this.dir
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}
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find() {
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for (let y = 0; y < map.length; y++) {
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for (let x = 0; x < map[y].length; x++) {
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if (map[y][x] === "^") return [y, x]
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}
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}
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}
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goStraight() {
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const [y, x] = this.position
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const [dy, dx] = this.dir
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this.position = [y + dy, x + dx]
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//const iWasAlreadyHere = this.visited.some(visits => visits.split()[0] === y + dy && visits.split()[1] === x + dx)
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if (!this.visited.includes(this.position)) this.visited.push(this.position)
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this.steps += 1
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}
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isLeaving() {
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const [y, x] = this.position
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const [dy, dx] = this.dir
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return x + dx < 0 || x + dx > map[0].length || y + dy < 0 || y + dy >= map.length
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}
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isBlockAhead() {
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const [y, x] = this.position
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const [dy, dx] = this.dir
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return map[y + dy][x + dx] === "#" ? true : false
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}
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isStillOnMap() {
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const [y, x] = this.position
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return (y >= 0 && y <= map.length) && (x >= 0 && x <= map[0].length)
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}
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solve1() {
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console.log("y", map.length, "x", map[0].length)
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this.visited = [this.position]
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while (this.isStillOnMap()) {
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if (this.isLeaving()) { console.log(`ran ${this.steps} steps`); break }
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if (this.isBlockAhead()) this.rotate()
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this.goStraight(this.dir)
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}
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this.visited = Array.from(new Set(this.visited.map(JSON.stringify)), JSON.parse);
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console.log(this.visited.length)
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}
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}
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init('input.txt') |