import fs from "fs";

const [directions, _, ...lines] = fs
  .readFileSync("./input.txt")
  .toString()
  .split("\n")
  .slice(0, -1);

const nodes = lines
  .map((line) => {
    const match = line.match(/(...) = \((...), (...)\)/);
    if (!match) throw new Error("Could not match");
    return {
      node: match[1],
      left: match[2],
      right: match[3],
    };
  })
  .map((node, index, nodes) => ({
    node: index,
    left: nodes.findIndex((n) => n.node === node.left),
    right: nodes.findIndex((n) => n.node === node.right),
  }));

const targetNumber = lines.findIndex((line) => line.startsWith("ZZZ"));
let currentNumber = lines.findIndex((line) => line.startsWith("AAA"));

let steps = 0;
while (currentNumber !== targetNumber) {
  const direction = (
    {
      L: "left",
      R: "right",
    } as const
  )[directions[steps % directions.length]];
  if (!direction) throw new Error("Invalid direction");

  currentNumber = nodes[currentNumber][direction];
  steps++;
}

console.log({ steps });