function q43()
{
// Compute the 3 digits values divisible by the given primes
$primes = [2, 3, 5, 7, 11, 13, 17];
$divisibleBy = [];
foreach ($primes as $prime) {
$divisibleBy[$prime] = [];
for ($i = $prime; $i < 1000; $i += $prime) {
// Exclude any multiple of a given prime if it is already not pandigital
if (!Number::isPandigital($i, null, true)) {
continue;
}
$divisibleBy[$prime][] = $i;
}
}
// Generate all the sequences of valid (respecting the constraint specified in the problem) pandigital numbers
$primeSize = count($primes);
$solutionSet = $divisibleBy[$primes[$primeSize - 1]];
for ($i = 1; $i < $primeSize; ++$i) {
$upperPart = $divisibleBy[$primes[$primeSize - $i - 1]];
// dwdxdy
$lowerPart = $solutionSet;
// dxdydz
// Map numbers for efficient matching
$a = [];
foreach ($upperPart as $number) {
$formattedNumber = sprintf('%02d', $number % 100);
$a[$formattedNumber][] = $number;
}
$b = [];
foreach ($lowerPart as $number) {
$formattedNumber = sprintf('%02d', floor($number / pow(10, $i)));
$b[$formattedNumber][] = $number;
}
$intersection = array_intersect_key($a, $b);
$newSolutionSet = [];
foreach ($intersection as $key => $dontCare) {
$upperPart = $a[$key];
$lowerPart = $b[$key];
foreach ($upperPart as $upper) {
$upper = floor($upper / 100);
foreach ($lowerPart as $lower) {
$lower = sprintf('%0' . (2 + $i) . 'd', $lower);
// Since the number has to be pandigital, make sure the digit we're about to add isn't already present
if (strpos($lower, (string) $upper) !== false) {
continue;
}
$value = $upper . $lower;
$newSolutionSet[] = $value;
}
}
}
$solutionSet = $newSolutionSet;
}
// Find the last digit for each solution in the solution set
$finalSolutionSet = [];
foreach ($solutionSet as $solution) {
for ($i = 0; $i < 10; ++$i) {
if (strpos($solution, (string) $i) !== false) {
continue;
}
$finalSolutionSet[] = $i . $solution;
break;
}
}
return array_sum($finalSolutionSet);
}
