#include <iostream>
#include <algorithm>
#include "euler_4.h"

/*
 * A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
 * Find the largest palindrome made from the product of two 3-digit numbers.
 */

inline bool isPalindrome(int n)
{
    std::string a = std::to_string(n);
    std::string b = a;
    std::reverse(b.begin(), b.end());
    return (a == b);
}

void euler_4()
{
    int Largest = -1, Num = -1;
    for (int i = 999; i >= 100; i--)
    {
        for (int j = i; j >= 100; j--)
        {
            Num = j * i;
            if (isPalindrome(Num))
            {
                if (Num > Largest)
                {
                    Largest = Num;
                }
            }
        }
    }

    std::cout << "The largest palindrome is " << Largest;
}