#include /* [ Usage Example (Code Playground) ] Enter the number(s) each separated by a space or line break (Enter). [ Challenge Description ] Given a number, find the nearest Palindrome number larger than the number given. © 2018 SoloLearn Community */ /* Function isPalindrome [Description] Checks whether if a number is a Palindrome number. LOG: [2018-04-04] Previously the function uses a rather inefficient way to obtain reversed number, worked its way as it would check Palindrome string. Modification was in order upon a suggestion from @Gordie. [Parameters] ll The number [Return value] bool, true when supplied number is Palindrome number. */ bool isPalindrome(const long long n) { // One digit cannot be Palindrome if(n > -11LL && n < 11LL) return false; long long reversed {n % 10}, nc {n}; // Now uses arithmetic calculation // to reverse the number. // [Suggested by @Gordie] while(nc /= 10) reversed = reversed * 10 + nc % 10; return n == reversed; } // Main procedure int main() { short found; long long n_orig; std::cout << "Enter an integer and we will find nearest Palindrome number less/greater than the number."; while(true) { std::cin >> n_orig; if(!std::cin.good()) break; found = 0; long long n0 = n_orig, n1 = n_orig; std::cout << "\n\nNumber: " << n0; do { if(!(found & 1) && isPalindrome(++n0)) { found |= 1; std::cout << "\nNearest Palindrome > " << n_orig << ": " << n0; } if(!(found & 2) && isPalindrome(--n1)) { found |= 2; std::cout << "\nNearest Palindrome < " << n_orig << ": " << n1; } if(n0 == n1) break; // just in case } while(found < 3); } return 0; }

Challenge - Nearest Palindrome