// TODO: optimization needed

// const input = "0,3,6";
const input = "9,3,1,0,8,4";

const start = input.split(",");
const memory = {};

let turn = 1;
let lastNum = null;

for (const num of start) {
  if (lastNum !== null) {
    memory[lastNum] = turn - 1;
  }
  lastNum = num;
  console.log(`Turn ${turn}: ${num}`);
  turn += 1;
}

let num;
let lastLog = new Date();
while (turn <= 30000000) {
  if (typeof memory[lastNum] === "undefined") {
    num = 0;
  } else {
    num = turn - 1 - memory[lastNum];
  }

  const now = new Date();
  if (now - lastLog > 5000) {
    console.log(`Turn ${turn.toLocaleString()}, num: ${num}`);
    lastLog = now;
  }

  memory[lastNum] = turn - 1;
  lastNum = num;
  turn += 1;
}

console.log("Solution:", num);