2018-3

$input = explode("\n", file_get_contents('3.txt'));
$count = count($input);
echo $count. " inputs\n";

foreach ($input as $i => $line) {
    preg_match('/#(\d+) @ (\d+),(\d+): (\d+)x(\d+)/', $line, $m);
    $rects[$m[1]] = ['x'=>$m[2], 'y'=>$m[3], 'x2'=>$m[2]+$m[4], 'y2'=>$m[3]+$m[5]];
}

$filled = [];
$unsets = array_fill(1, 1309, 1);

for ($i=1; $i <= $count-1; $i++) {
    $rect1 = $rects[$i];
    for ($j=$i+1; $j <= $count; $j++) {
        $rect2 = $rects[$j];
        if ($rect1['x']<$rect2['x2'] and $rect1['x2']>$rect2['x'] and $rect1['y']<$rect2['y2'] and $rect1['y2']>$rect2['y']) {
            $overlap = [
                'x'  => max($rect1['x'],  $rect2['x']),
                'x2' => min($rect1['x2'], $rect2['x2']),
                'y'  => max($rect1['y'],  $rect2['y']),
                'y2' => min($rect1['y2'], $rect2['y2']),
            ];
            for ($ox=$overlap['x']; $ox < $overlap['x2']; $ox++) { 
                for ($oy=$overlap['y']; $oy < $overlap['y2']; $oy++) { 
                    $filled[$ox.'_'.$oy] = 1;
                }
            }
            unset($unsets[$i], $unsets[$j]);
        }
    }
}

echo count($filled);
printDebug($unsets);