3rd and 2nd day

03/part2.php

@@ -0,0 +1,11 @@
+<?php
+
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$input = array_map(fn($line) => str_split($line), $input);
+$gamma = $epsilon = [];
+for ($i = 0; $i < count($input[0]); $i++) {
+    $bit = (int) (array_sum($column = array_column($input, $i)) >= ceil(count($column) / 2));
+    $gamma[] = $bit;
+    $epsilon[] = ~$bit & 1;
+}
+echo bindec(implode('', $gamma)) * bindec(implode('', $epsilon)).PHP_EOL;