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  1. #include <iostream>
  2. #include <cmath>
  3.  
  4. using namespace std;
  5.  
  6.  
  7. inline bool is_palindrome(uint64_t n, uint64_t k)
  8. {
  9. 	if (n < 10 && k < 10)
  10. 		return true;
  11. 	int first_digit = n / k;
  12. 	int last_digit = n % 10;
  13. 	if (first_digit == last_digit)
  14. 		return is_palindrome((n % k) / 10, k / 100);
  15. 	else
  16. 		return false;
  17. }
  18.  
  19. inline uint64_t get_divider(uint64_t n)
  20. {
  21. 	uint64_t divider = 1;
  22. 	while (n / divider >= 10){
  23. 		divider *= 10;
  24. 	}
  25.  
  26. 	return divider;
  27. }
  28.  
  29. int main() {
  30. 	int length = 3;
  31. 	int max = std::pow(10, length) - 1;
  32. 	int min = std::pow(10, length - 1) - 1;
  33.  
  34. 	//cout << max << ":" << min;
  35.  
  36. 	uint64_t max_palindrome = 0;
  37. 	uint64_t n1, n2 = max;
  38. 	for (uint64_t i = max; i > min; i--)
  39. 	{
  40. 		for (uint64_t j = max; j >= min; j--)
  41. 		{
  42. 			//cout << i << "*" << j << endl;
  43. 			uint64_t number = i * j;
  44. 			if (is_palindrome(number, get_divider(number)))
  45. 			{
  46. 				if (number > max_palindrome)
  47. 				{
  48. 					max_palindrome = number;
  49. 					n1 = i;
  50. 					n2 = j;
  51. 					cout << n1 << "*" << n2 << "=" << max_palindrome <<endl;
  52. 				}
  53. 			}	
  54. 		}
  55. 	}
  56. 	cout << n1 << "*" << n2 << "=" << max_palindrome <<endl;
  57. 	return 0;
  58. }
Success #stdin #stdout 0.12s 3456KB
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Standard input is empty
stdout
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995*583=580085
993*913=906609
993*913=906609
https://ideone.com/kv2f7z
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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