257 lines
6.1 KiB
JavaScript
257 lines
6.1 KiB
JavaScript
import { readFileSync } from 'node:fs';
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const input = readFileSync('input', 'utf-8');
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const [mapData, pathData] = input.split('\n\n');
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const F = {
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R: 0,
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D: 1,
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L: 2,
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U: 3,
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invert: (facing) => {
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switch (facing) {
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case F.R: return F.L;
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case F.D: return F.U;
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case F.L: return F.R;
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case F.U: return F.D;
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}
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},
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rotateR: (facing) => {
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switch (facing) {
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case F.R: return F.D;
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case F.D: return F.L;
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case F.L: return F.U;
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case F.U: return F.R;
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}
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},
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rotateL: (facing) => {
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switch (facing) {
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case F.R: return F.U;
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case F.U: return F.L;
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case F.L: return F.D;
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case F.D: return F.R;
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}
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}
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};
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class Map {
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constructor(mapData) {
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this.data = mapData
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.split('\n')
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.filter(line => !!line.trim());
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this.height = this.data.length;
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this.width = this.data.reduce((max, row) => Math.max(max, row.length), 0);
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this.portals = {};
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}
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get startingPosition() {
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const pos = [1, 1];
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while (this.get(...pos) !== '.') {
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pos[0]++;
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}
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return pos;
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}
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cubeMode() {
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if (this.width !== 150 || this.height !== 200) {
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throw new Error('Cube mode only works with full size map');
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}
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this.portals = {};
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const e1 = this._edge([51, 1], [100, 1]);
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const e2 = this._edge([101, 1], [150, 1]);
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const e3 = this._edge([51, 1], [51, 50]);
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const e4 = this._edge([150, 1], [150, 50]);
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const e5 = this._edge([101, 50], [150, 50]);
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const e6 = this._edge([51, 51], [51, 100]);
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const e7 = this._edge([100, 51], [100, 100]);
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const e8 = this._edge([1, 101], [50, 101]);
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const e9 = this._edge([1, 101], [1, 150]);
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const e10 = this._edge([100, 101], [100, 150]);
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const e11 = this._edge([51, 150], [100, 150]);
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const e12 = this._edge([1, 151], [1, 200]);
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const e13 = this._edge([50, 151], [50, 200]);
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const e14 = this._edge([1, 200], [50, 200]);
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this._portalEdge(e1, F.U, e12, F.R);
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this._portalEdge(e2, F.U, e14, F.U);
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this._portalEdge([...e3].reverse(), F.L, e9, F.R);
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this._portalEdge([...e4].reverse(), F.R, e10, F.L);
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this._portalEdge(e5, F.D, e7, F.L);
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this._portalEdge(e6, F.L, e8, F.D);
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this._portalEdge(e11, F.D, e13, F.L);
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}
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flatMode() {
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this.portals = {};
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for (let row = 1; row <= this.height; row++) {
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let col = 1;
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while (this.get(col, row) === ' ') col++;
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const start = [col, row];
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while (this.get(col + 1, row) !== ' ') col++;
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const end = [col, row];
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this.portals[[start, F.L]] = [end, F.L];
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this.portals[[end, F.R]] = [start, F.R];
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}
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for (let col = 1; col <= this.width; col++) {
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let row = 1;
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while (this.get(col, row) === ' ') row++;
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const start = [col, row];
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while (this.get(col, row + 1) !== ' ') row++;
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const end = [col, row];
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this.portals[[start, F.U]] = [end, F.U];
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this.portals[[end, F.D]] = [start, F.D];
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}
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}
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get(col, row) {
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const x = col - 1;
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const y = row - 1;
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if (y < 0 || y >= this.data.length || x < 0 || x >= this.data[y].length) {
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return ' ';
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}
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return this.data[y][x];
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}
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nextPos(pos, facing) {
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if (this.portals[[pos, facing]]) return this.portals[[pos, facing]];
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return [[
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pos[0] + (facing === F.R ? 1 : (facing === F.L ? -1 : 0)),
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pos[1] + (facing === F.D ? 1 : (facing === F.U ? -1 : 0)),
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], facing];
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}
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_portalEdge(fromEdge, fromFacing, toEdge, toFacing) {
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if (fromEdge.length !== toEdge.length) {
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throw new Error('fromEdge must be the same length as toEdge');
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}
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for (let i = 0; i < fromEdge.length; i++) {
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const fromPos = fromEdge[i];
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const toPos = toEdge[i];
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this.portals[[fromPos, fromFacing]] = [toPos, toFacing];
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this.portals[[toPos, F.invert(toFacing)]] =
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[fromPos, F.invert(fromFacing)];
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}
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}
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_edge(start, end) {
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if (start[0] !== end[0] && start[1] !== end[1]) {
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throw new Error("Edges can't be diagonal");
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}
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const colDiff = end[0] - start[0];
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const colIncr = colDiff / (Math.abs(colDiff) || 1);
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const rowDiff = end[1] - start[1];
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const rowIncr = rowDiff / (Math.abs(rowDiff) || 1);
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const edge = [];
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let col = start[0];
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let row = start[1];
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edge.push([col, row]);
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do {
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col += colIncr;
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do {
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row += rowIncr;
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edge.push([col, row]);
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} while (row !== end[1])
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} while (col !== end[0])
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return edge;
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}
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}
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class Walker {
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constructor(map) {
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this.map = map;
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this.facing = F.R;
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this.pos = this.map.startingPosition;
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}
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walk(paces) {
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for (let p = 0; p < paces; p++) {
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const [nextPos, nextFacing] = this.map.nextPos(this.pos, this.facing);
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let nextTile = this.map.get(...nextPos);
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if (nextTile === ' ') {
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throw new Error('Escaped Map!');
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}
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if (nextTile === '#') {
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break;
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}
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this.pos = nextPos;
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this.facing = nextFacing;
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}
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}
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get password() {
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return (
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this.pos[1] * 1000 +
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this.pos[0] * 4 +
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this.facing
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);
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}
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rotateCounterclockwise() {
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this.facing = F.rotateL(this.facing);
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}
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rotateClockwise() {
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this.facing = F.rotateR(this.facing);
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}
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}
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const instructions = pathData
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.split('\n')
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.filter(line => !!line.trim())
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.join('')
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.split(/(L|R)/)
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.filter(instruction => !!instruction.trim())
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.map(instruction => {
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const num = parseInt(instruction);
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return isNaN(num) ? instruction : num
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});
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function runInstructions(walker) {
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for (const instruction of instructions) {
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if (typeof instruction === 'number') {
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walker.walk(instruction);
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} else if (instruction === 'L') {
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walker.rotateCounterclockwise();
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} else if (instruction === 'R') {
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walker.rotateClockwise();
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} else {
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throw new Error(`Invalid instruction: ${instruction}`);
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}
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}
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}
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const map = new Map(mapData);
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map.flatMode();
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const flatWalker = new Walker(map);
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runInstructions(flatWalker);
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console.log('The password for the flat map is:', flatWalker.password);
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map.cubeMode();
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const cubeWalker = new Walker(map)
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runInstructions(cubeWalker);
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console.log('The password for the cube map is:', cubeWalker.password);
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