const fs = require('fs/promises');

const sum = (arr) => arr.reduce((total, num) => total+num, 0);
const arrayOfLength = n => Array.from(Array(n).keys()).map(() => {});
const modulo = (n, m) => ((n % m + m) % m);

const keypress = async () => {
  process.stdin.setRawMode(true)
  return new Promise(resolve => process.stdin.once('data', data => {
    const byteArray = [...data]
    if (byteArray.length > 0 && byteArray[0] === 3) {
      console.log('^C')
      process.exit(1)
    }
    process.stdin.setRawMode(false)
    resolve()
  }))
}

const coords = ([x, y, z]) => `${x},${y},${z}`;

const createNode = (arr, order, first, par, i = 0) => {
  const node = {
    val: arr[i],
    par
  }
  order.push(node);
  if(i < arr.length - 1) {
    node.next = createNode(arr, order, first || node, node, i+1)
    return node;
  }
  first.par = node;
  node.next = first;
  node.last = true;
  return node;
};

const print = (node, first) => node === first ? [] : [node.val, ...print(node.next, first || node)];

const key = 811589153;

const main = async () => {
  const input = (await fs.readFile("./input.txt", 'utf8')).slice(0, -1).split("\n").map(x => parseInt(x) * key);

  const order = [];
  let head = createNode(input, order, 0);

  const shiftIntoOffset = (node, offset) => {
    if(offset === 0) {
      return;
    }

    let replace = node.next;
    node.par.next = replace;
    replace.par = node.par;
    if(node === head) {
      head = node.next;
    }

    for(let i = 0; i < offset; ++i) {
      replace = replace.next;
    }
    if(replace === head) {
      head = node;
    }
    replace.par.next = node;
    node.par = replace.par;
    node.next = replace;
    replace.par = node;
    return;
  }

  const mix = () => {
    for(let i = 0; i < order.length; i++) {
      const node = order[i];

      const shiftBy = modulo(node.val, input.length - 1);

      if(shiftBy !== 0) {
        shiftIntoOffset(node, shiftBy);
      }
    }
  };
  for(let i = 0; i < 10; ++i) {
    mix();
  }

  console.log("Mixed!");
  const getAnswer = () => {
    const answer = [];
    let node = order.find(x => 0 === x.val);
    let i = 0;
    while(answer.length < 3) {
      if(i === 1000 % input.length
        || i === 2000 % input.length
        || i === 3000 % input.length
      ) {
          answer.push(node.val);
      }
      node = node.next;
      ++i;
    }
    return answer;
  };
  console.log("Answer: ", sum(getAnswer()));
}


main();