import { readFileSync } from "fs"; const t0 = performance.now(); const bends = { "|": [ [0, -1], [0, 1], ], "-": [ [-1, 0], [1, 0], ], L: [ [0, -1], [1, 0], ], J: [ [0, -1], [-1, 0], ], 7: [ [-1, 0], [0, 1], ], F: [ [1, 0], [0, 1], ], S: [ [1, 0], [0, 1], [-1, 0], [0, -1], ], }; const relPos = (pos, x, y) => pos.some((e) => e[0] === x && e[1] === y); const compare = (a, b) => a.x === b.x && a.y === b.y; const input = readFileSync("input.txt") .toString() .split("\n") .filter((e) => e.length > 0) .map((e) => e.split("")); const startY = input.findIndex((e) => e.includes("S")); const startX = input[startY].findIndex((e) => e === "S"); const open = [ { distance: 0, symbol: "S", x: startX, y: startY, }, ], closed = []; while (open.length > 0) { const current = open.shift(); closed.push(current); const directions = bends[current.symbol]; for (let j = -1; j < 2; j++) for (let i = -1; i < 2; i++) { if (!relPos(directions, i, j)) continue; const { x, y, distance } = current; const [nx, ny] = [x + i, y + j]; const symbol = input[ny][nx]; const nd = distance + 1; const next = { distance: nd, symbol, x: nx, y: ny, }; if (!relPos(bends[symbol], -i, -j)) continue; if (closed.some((e) => compare(e, next))) continue; open.push(next); } } const furthest = closed.sort((a, b) => b.distance - a.distance)[0]; console.log(furthest.distance); const t1 = performance.now(); console.log(`Runtime: ${t1 - t0}ms`);