// 4
const reverseArray = arr => {
  let newArr = [];
  for (let number of arr) {
    newArr.unshift(number);
  }
  return newArr;
};

console.log(reverseArray([1, 2, 1, 0]));

// 5
const palindrome = input => {
  const textInputArr = input
    .toLowerCase()
    .split('')
    .filter(sign => sign.match(/[a-z]/i));
  for (let i = 0, j = textInputArr.length - 1; i < j; i++, j--) {
    if (textInputArr[i] !== textInputArr[j]) return console.log('NO');
  }
  console.log('YES');
};

palindrome('4ABabA%');

// 6
const permutation = (arr1, arr2) => {
  const newArr1 = [...arr1];
  if (arr1.length !== arr2.length) return console.log('NO');
  for (let number of arr2) {
    const index = newArr1.indexOf(number);
    if (index > -1) newArr1.splice(index, 1);
  }
  if (newArr1.length > 0) return console.log('NO');
  console.log('YES');
};

permutation([1, 2, 3, 5, 4], [2, 4, 3, 1, 5]);

// 8
const findingPrimes = (n, m) => {
  const isPrime = n => {
    if (n <= 3) return n > 1;
    else if (n % 2 === 0 || n % 3 === 0) return false;
    let i = 5;
    while (i * i <= n) {
      if (n % i === 0 || n % (i + 2) === 0) return false;
      i += 6;
    }
    return true;
  };

  let numberOfPrimes = 0;
  for(let i = n; i <= m; i++) {
    if (isPrime(i)) numberOfPrimes++;
  }
  return numberOfPrimes;
};

console.log(findingPrimes(1, 10));