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import { JSONSet, Vec2, l2Norm, isDiagAdj } from "@/utils";
export const main = async (lines: string[]): Promise<number | string> => {
const knots: Vec2[] = Array(10)
.fill(null)
.map(() => ({ x: 0, y: 0 }));
const visited: JSONSet<Vec2> = new JSONSet();
visited.add(knots[0]);
for (const step of lines) {
const [dir, steps_s] = step.split(" ");
const steps = parseInt(steps_s);
for (let i = 0; i < steps; ++i) {
if (dir === "U") knots[0].y += 1;
if (dir === "L") knots[0].x -= 1;
if (dir === "R") knots[0].x += 1;
if (dir === "D") knots[0].y -= 1;
for (let knotidx = 1; knotidx < knots.length; knotidx++) {
const [head, tail] = [knots[knotidx - 1], knots[knotidx]];
if (!isDiagAdj(head, tail)) {
if (head.y - tail.y === 0) {
tail.x += Math.floor((head.x - tail.x) / 2);
} else if (head.x - tail.x === 0) {
tail.y += Math.floor((head.y - tail.y) / 2);
} else {
tail.x += head.x - tail.x > 0 ? 1 : -1;
tail.y += head.y - tail.y > 0 ? 1 : -1;
}
}
if (knotidx === knots.length - 1) {
visited.add(tail);
}
}
}
}
return visited.size;
};
//
const isrun = process.argv.length > 1 && process.argv[1] === import.meta.path;
if (isrun) {
const file = Bun.file("./problem.txt");
const text = await file.text();
const lines = text.split("\n").filter((x) => x && x.length);
console.log("=== COMPUTATION ===\n");
const answer = await main(lines);
console.log("\n=== /COMPUTATION ===\n");
console.log("=== ANSWER TO P2 ===");
console.log(answer);
}
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