LeetCode: Super Palindromes Solution
1/**2 * @param {string} left3 * @param {string} right4 * @return {number}5 */6var superpalindromesInRange = function (left, right) {7 ;[left, right] = [+left, +right]89 const isPalindrome = s => s === s.split("").reverse().join("")1011 let palindromes = [1, 2, 3, 4, 5, 6, 7, 8, 9]12 // as range is max of 1e18 => find from sqrt(1e18) = 1e913 // build palindrome from concatnate: xx, x0x, x1x,...x9x14 // so x must be in range 9/2 = 415 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 }2324 palindromes = palindromes.map(Number).sort((a, b) => a - b)2526 let numberOfSuperPalindromesInRange = 02728 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 }3435 return numberOfSuperPalindromesInRange36}
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leetcode
math
string
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