107 lines
2.9 KiB
TypeScript
107 lines
2.9 KiB
TypeScript
const fs = require('fs');
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const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
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interface Coord {
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x: number,
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y: number,
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};
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enum Dir {
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Up,
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Right,
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Down,
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Left,
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};
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const map: Array<Array<string>> = input.split("\n").map((row: string) => row.split(''));
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const width = map[0].length;
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const height = map.length;
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const startIndex = input.indexOf('S');
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let startPos = { x: startIndex % (width + 1), y: Math.floor(startIndex / height) };
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function get(pos: Coord): string {
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if (map[pos.y] && map[pos.y][pos.x]) {
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return map[pos.y][pos.x];
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}
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return '#';
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}
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function set(pos: Coord, val: string): void {
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map[pos.y][pos.x] = val;
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}
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function nextDir(dir: Dir): Dir {
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const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
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const i = (directions.indexOf(dir) + 1) % directions.length;
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return directions[i];
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}
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function prevDir(dir: Dir): Dir {
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const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
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const i = directions.indexOf(dir) - 1;
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if (i < 0) {
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return directions[directions.length - 1];
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}
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return directions[i];
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}
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function nextCoord(pos: Coord, direction: Dir): Coord {
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return direction === Dir.Up ? { x: pos.x, y: pos.y - 1 }
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: (direction === Dir.Right ? { x: pos.x + 1, y: pos.y }
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: (direction === Dir.Down ? { x: pos.x, y: pos.y + 1 } : { x: pos.x - 1, y: pos.y })
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);
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}
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const shortCuts: Array<number> = [];
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const pathCoords: Array<Coord> = [startPos];
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const cheatTime = 20;
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const minShortCut = 100;
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let speedMap: { [key: string]: number } = {};
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function findShortCuts(pos: Coord): void {
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for (let i = 0; i < pathCoords.length - minShortCut; i++) {
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const possibleSC = pathCoords[i];
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const dx = possibleSC.x - pos.x;
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const dy = possibleSC.y - pos.y;
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const cheatLength = Math.abs(dx) + Math.abs(dy);
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if (cheatLength <= cheatTime) {
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const shortCutLength = pathCoords.length - i - cheatLength;
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if (shortCutLength >= minShortCut) {
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shortCuts.push(shortCutLength);
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}
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}
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}
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}
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for (let dir of [Dir.Up, Dir.Right, Dir.Down, Dir.Left]) {
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if (get(nextCoord(startPos, dir)) === '.') {
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let pos = startPos;
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loop:
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while (true) {
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for (let newDir of [dir, nextDir(dir), prevDir(dir)]) {
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const next = nextCoord(pos, newDir);
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const nextStr = `${next.x},${next.y}`;
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const nextChar = get(next);
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if (nextChar === 'E') {
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findShortCuts(next);
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pathCoords.push(next);
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break loop;
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} else if (nextChar === '.') {
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findShortCuts(next);
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pathCoords.push(next);
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pos = next;
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dir = newDir;
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break;
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}
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};
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}
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break;
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}
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}
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console.log(shortCuts.length); |