Project Euler – Problem 4 Solution

Problem: 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.
* https://projecteuler.net/problem=4

Php;

<?php

/**
 * Checks number if palindrome or not!
 *
 * @param $number
 * @return bool
 */
function check_if_palindrome($number)
{
    $is_palindrome = true;
    $array  = array_map('intval', str_split($number));
    $array2  = array_map('intval', str_split($number));
    $array2_count = count($array2) - 1;
    foreach ($array as $index => $item) {
        if ($item !== $array2[$array2_count - $index]) {
            $is_palindrome = false;
        }
    }
    return $is_palindrome;
}

$value = 0;
for ($i = 100; $i < 1000; $i++) {
    for ($k = 100; $k < 1000; $k++) {
        $result = $k * $i;
        if (check_if_palindrome($result) && $result > $value) {
            $value = $result;
        }
    }
}
echo $value;

Javascript;

'use strict';

/**
 * Checks number if palindrome or not!
 * @param number
 */
function check_if_palindrome(number) {
    var is_palindrome = true,
        array = (""+number).split(""),
        array2 = (""+number).split(""),
        array2_count = array2.length - 1;

    for (var i = 0; i < array2_count; i++) {
        if (array[i] !== array2[array2_count - i]) {
            is_palindrome = false;
        }
    }

    return is_palindrome;
}

var value = 0;
for (var i = 100; i < 1000; i++) {
    for (var k = 100; k < 1000; k++) {
        var result = k * i;
        if (check_if_palindrome(result) && result > value) {
            value = result;
        }
    }
}

console.log(value);