✨ Add day 8

day_8/part_1.php

@@ -0,0 +1,25 @@
+<?php
+
+$input = file_get_contents('input.txt');
+
+const WIDTH = 25;
+const HEIGHT = 6;
+$area = WIDTH * HEIGHT;
+
+$layers = array_map(static function($layer) {
+    return str_split($layer);
+}, str_split($input, $area));
+
+usort($layers, function($layer_a, $layer_b) {
+    $a0 = array_count_values($layer_a)['0'];
+    $b0 = array_count_values($layer_b)['0'];
+    if ($a0 === $b0) {
+        return 0;
+    }
+    return  $a0 < $b0 ? -1 : 1 ;
+});
+
+reset($layers);
+$fewest_0_layer = current($layers);
+
+echo array_count_values($fewest_0_layer)['1'] * array_count_values($fewest_0_layer)['2'];