const input = [
  { value: 'ss  i', order: 2, expired: true },
  { value: 'evol', order: 3, expired: true },
  { value: 'ff kciuq', order: 1, expired: false },
  { value: 'te j j　', order: 5, expired: false },
  { value: 'xooff', order: 4, expired: false },
];

const solution1 = (arr) => arr
.filter(it => !it.expired)
.sort((a, b) => a.order - b.order)
.reduce((acc, it) => {
  acc += it.value.split('').reverse().join('');
  acc = Array.from(new Set(acc)).join('')
  return acc;
},'');

const solution2 = (arr) => {
  let result = '';

  const sortedArr = arr.slice().sort((a, b) => a.order - b.order);

  sortedArr.forEach(it => {
    if (!it.expired) {
      result += it.value.split('').reverse().join('');
    }
  });

  return [...new Set(result)].join('');
}

const solution3 = (arr) => {
  return arr
    .filter(({ expired }) => !expired)
    .sort((a, b) => a.order - b.order)
    .reduce((acc, res) => {
        acc.push(...res.value.split('').reverse());
        return Array.from(new Set(acc));
      }, [])
    .join('');
};

const solution4 = (arr) => {
  const result = arr
  .filter((it) => !it.expired)
  .sort((a, b) => a.order - b.order)
  .reduce((acc, res) => {
    acc.push(...res.value.split('').reverse());
    return acc;
  }, []);
  return Array.from(new Set(result)).join('');
}