2331 반복수열

const fs = require('fs');
const filePath = process.platform === 'linux' ? 'dev/stdin' : '../input.txt';
const [a, p] = fs.readFileSync(filePath).toString('utf-8').trim().split(' ').map(Number);

const arr = [a];
while (true) {
  const cur = String(arr[arr.length - 1]);
  const next = cur.split('').reduce((acc, v) => acc + Math.pow(v, p), 0);
  if (arr.includes(next)) {
    // 하나라도 같은 수가 존재한다면
    console.log(arr.indexOf(next));
    break;
  }
  arr.push(next);
}