100 lines
2.8 KiB
TypeScript
100 lines
2.8 KiB
TypeScript
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import { BinaryHeap } from "jsr:@std/data-structures/binary-heap";
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export type Map = string[][];
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export async function readMap(path: string): Promise<Map> {
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const text = await Deno.readTextFile(path);
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return text.trim().split("\n").map((line) => line.trim().split(""));
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}
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export function displayMap(map: Map): void {
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console.log(map.map((line) => line.join("")).join("\n"));
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}
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export type Position = [number, number];
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export type Face = 0 | 1 | 2 | 3;
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export type RotateDir = "clockwise" | "counter-clockwise";
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export function rotateFace(face: Face, dir: RotateDir): Face {
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if (dir === "clockwise") {
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return ((face + 1) % 4) as Face;
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} else {
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return ((face + 3) % 4) as Face;
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}
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}
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export function faceToStr(face: Face): string {
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return ["E", "S", "W", "N"][face];
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}
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export function strToFace(str: string): Face {
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const face = ["E", "S", "W", "N"].indexOf(str);
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if (face === -1) {
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throw new Error(`Invalid face: ${str}`);
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}
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return face as Face;
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}
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export function moveForward([x, y]: Position, face: Face): Position {
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switch (face) {
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case 0: return [x + 1, y];
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case 1: return [x, y + 1];
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case 2: return [x - 1, y];
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case 3: return [x, y - 1];
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}
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}
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// S is start
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// E is end
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// # is wall
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// first face the east
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export class Solver {
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readonly map: Map;
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constructor(map: Map) {
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this.map = map;
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}
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public minCost([x,y]: [number, number], face: Face): number {
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const heap = new BinaryHeap<[Position, Face, number]>(
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([, , cost1], [, , cost2]) => cost1 - cost2
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);
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const visited = new Set<string>();
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heap.push([[x, y], face, 0]);
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while (heap.length > 0) {
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const [[x, y], face, cost] = heap.pop()!;
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if (this.map[y][x] === "E") {
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return cost;
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}
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if (this.map[y][x] === "#") {
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continue;
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}
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const key = `${x},${y},${face}`;
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if (visited.has(key)) {
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continue;
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}
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visited.add(key);
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for (const dir of ["clockwise", "counter-clockwise"] as RotateDir[]) {
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heap.push([[x, y], rotateFace(face, dir), cost + 1000]);
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}
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heap.push([moveForward([x, y], face), face, cost + 1]);
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}
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return -1;
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}
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findStart(): Position {
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for (let y = 0; y < this.map.length; y++) {
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for (let x = 0; x < this.map[y].length; x++) {
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if (this.map[y][x] === "S") {
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return [x, y];
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}
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}
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}
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throw new Error("No start found");
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}
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}
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if (import.meta.main) {
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const map = await readMap("input.txt");
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displayMap(map);
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const solver = new Solver(map);
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const start = solver.findStart();
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console.log(solver.minCost(start, strToFace("E")));
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}
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