# Super Palindromes Problem

## Description

LeetCode Problem 906.

Let’s say a positive integer is a super-palindrome if it is a palindrome, and it is also the square of a palindrome.

Given two positive integers left and right represented as strings, return the number of super-palindromes integers in the inclusive range [left, right].

Example 1:

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Input: left = "4", right = "1000"
Output: 4
Explanation: 4, 9, 121, and 484 are superpalindromes.
Note that 676 is not a superpalindrome: 26 * 26 = 676, but 26 is not a palindrome.
``````

Example 2:

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Input: left = "1", right = "2"
Output: 1
``````

Constraints:

• 1 <= left.length, right.length <= 18
• left and right consist of only digits.
• left and right cannot have leading zeros.
• left and right represent integers in the range [1, 10^18 - 1].
• left is less than or equal to right.

## Sample C++ Code

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class Solution {
public:
bool check(long long n) {
long long num = n, rev = 0, digit;
do {
digit = num % 10;
rev = (rev * 10) + digit;
num = num / 10;
} while (num != 0);

return rev == n;
}

long long nextPalindrome(long long palindrome, long long num) {
// if num = 123 this function will return 123321
while (num > 0) {
palindrome = palindrome * 10 + (num % 10);
num /= 10;
}
return palindrome;
}

vector<long long> generatePalindromes(long long left, long long right) {
vector<long long> res;
long long number;
for (int i = 1; (number = nextPalindrome(i, i / 10)) <= right; i++) {
if (number >= left && number <= right)
// odd palindrome
res.push_back(number);
number = nextPalindrome(i, i);
if (number >= left && number <= right)
// even palindrome
res.push_back(number);
}
return res;
}

int superpalindromesInRange(string left, string right) {
long long r = stoull(right), l = stoull(left);
int cnt = 0;
for (auto &ul : generatePalindromes(sqrt(l), sqrt(r)))
if (check(ul * ul))
cnt++;
return cnt;
}
};
``````