'; $input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES); $input = array_map(fn($line) => explode(',', str_replace(' -> ', ',', $line)), $input); $map = array_fill(0, 1000, array_fill(0, 1000, 0)); foreach ($input as $coordinates) { if ($coordinates[0] == $coordinates[2]) { $start = min([$coordinates[1], $coordinates[3]]); $end = max([$coordinates[1], $coordinates[3]]); for ($i = $start; $i <= $end; $i++) { $map[$coordinates[0]][$i]++; } } if ($coordinates[1] == $coordinates[3]) { $start = min([$coordinates[0], $coordinates[2]]); $end = max([$coordinates[0], $coordinates[2]]); for ($i = $start; $i <= $end; $i++) { $map[$i][$coordinates[1]]++; } } } echo count(array_filter(call_user_func_array('array_merge', $map), fn($el) => $el > 1)); //5632