advent_of_code_2020/day_16/part_1.php
2020-12-16 12:09:48 +01:00

58 lines
1.5 KiB
PHP

<?php
[$instructions, $mine, $others] = explode("\n\n", file_get_contents('input.txt'));
// parse instructions
function parseInstructions($instructions)
{
// class: 1-3 or 5-7
preg_match_all('/^[a-z]+: (\d+)-(\d+) or (\d+)-(\d+)$/mi', $instructions, $matches);
if (count($matches) !== 5) {
echo sprintf('Regex failed : %s', var_export($matches, true));
exit;
}
$compares = [];
array_shift($matches);
for ($i = 0, $l = count($matches[0]); $i < $l; $i++) {
$compares[] = static function ($number) use ($matches, $i) {
$comparison = ($number >= (int)$matches[0][$i] and $number <= (int)$matches[1][$i])
|| ($number >= (int)$matches[2][$i] and $number <= (int)$matches[3][$i]);
if ($comparison === true) {
return true;
}
return $number;
};
}
return $compares;
}
$compares = parseInstructions($instructions);
// check others
$others = explode("\n", $others);
array_shift($others);
$others = array_map(static function($other) {
return explode(',', $other);
}, $others);
$sum = 0;
foreach ($others as $other) {
foreach ($other as $number) {
$is_valid = false;
foreach ($compares as $compare) {
if ($compare((int)$number) === true) {
$is_valid = true;
break;
}
}
if (!$is_valid) {
$sum += $number;
echo sprintf('%u not in comparison list%s', $number, "\n");
}
}
}
// sum it up
echo $sum;