function sumAmicableNumbers($max)
{
$sum = 0;
for ($i = 1; $i < $max; ++$i) {
if (isAmicable($i)) {
$sum += $i;
}
}
return $sum;
}
include "helper.php";
function sumFactors($num)
{
$factors = array(1);
for ($i = $num - 1; $i > 1; $i--) {
if ($num % $i == 0) {
$factors[] = $i;
}
}
return array_sum($factors);
}
function isAmicable($a, $b)
{
if (sumFactors($b) == $a && $a != $b) {
return true;
} else {
return false;
}
}
$amicable = array();
for ($a = 1; $a <= 10000; $a++) {
if (!in_array($a, $amicable)) {
$b = sumFactors($a);
if (isAmicable($a, $b)) {
$amicable[] = $a;
$amicable[] = $b;
}
}
}
$total = array_sum($amicable);
result(31626, $total);