Question

I need to display first 80 palindromes and squares of those palindromes has to be also a palindromes (for example, 11 is palindrome and its square 121 is also a palindrome),

I already figured out how to output the palindromes but i dont know what to do next. using c++, loops.

Answer 1

Answer:

Explanation:

// C++ implementation of the  

// above approach  

#include <bits/stdc++.h>  

using namespace std;  

 

// check if a number is a palindrome  

bool ispalindrome(int x)  

{  

   int ans = 0;  

   int temp = x;  

   while (temp > 0)  

   {  

       ans = 10 * ans + temp % 10;  

       temp = temp / 10;  

   }  

   return ans == x;  

}  

 

// Function to return required count  

// of palindromes  

int SuperPalindromes(int L, int R)  

{  

   // Range [L, R]  

 

   // Upper limit  

   int LIMIT = 100000;  

 

   int ans = 0;  

 

   // count odd length palindromes  

   for (int i = 0 ;i < LIMIT; i++)  

   {  

       string s = to_string(i); // if s = '1234'  

 

       string rs = s.substr(0, s.size() - 1);  

       reverse(rs.begin(), rs.end());  

 

       // then, t = '1234321'  

       string p = s + rs;  

       int p_sq     = pow(stoi(p), 2);  

       if (p_sq > R)  

           break;  

       if (p_sq >= L and ispalindrome(p_sq))  

           ans = ans + 1;  

   }  

 

   // count even length palindromes  

   for (int i = 0 ;i < LIMIT; i++)  

   {  

       string s = to_string(i); // if s = '1234'  

 

       string rs = s;  

       reverse(rs.begin(), rs.end());  

       string p = s + rs; // then, t = '12344321'  

       int p_sq = pow(stoi(p), 2);  

       if (p_sq > R)  

           break;  

       if (p_sq >= L and ispalindrome(p_sq))  

           ans = ans + 1;  

   }  

 

   // Return count of super-palindromes  

   return ans;  

}  

 

// Driver Code  

int main()  

{  

   string L = "4";  

   string R = "1000";  

     

   // function call to get required answer  

   printf("%d\n", SuperPalindromes(stoi(L),  

                                 stoi(R)));  

   return 0;  

}  

 

// This code is contributed  

// by Akshat Singh