LeetCode: Super Palindromes Solution

1/**
2 * @param {string} left
3 * @param {string} right
4 * @return {number}
5 */
6var superpalindromesInRange = function (left, right) {
7  ;[left, right] = [+left, +right]
8
9  const isPalindrome = s => s === s.split("").reverse().join("")
10
11  let palindromes = [1, 2, 3, 4, 5, 6, 7, 8, 9]
12  // as range is max of 1e18 => find from sqrt(1e18) = 1e9
13  // build palindrome from concatnate: xx, x0x, x1x,...x9x
14  // so x must be in range 9/2 = 4
15  for (let i = 1; i < 10000; i++) {
16    const s1 = String(i) + String(i).split("").reverse().join("")
17    palindromes.push(s1)
18    for (let j = 0; j < 10; j++) {
19      const s2 = String(i) + String(j) + String(i).split("").reverse().join("")
20      palindromes.push(s2)
21    }
22  }
23
24  palindromes = palindromes.map(Number).sort((a, b) => a - b)
25
26  let numberOfSuperPalindromesInRange = 0
27
28  for (const palindrome of palindromes) {
29    const s = String(BigInt(palindrome) ** 2n)
30    if (isPalindrome(s) && left <= Number(s) && Number(s) <= right) {
31      numberOfSuperPalindromesInRange++
32    }
33  }
34
35  return numberOfSuperPalindromesInRange
36}