✨ Finit le jour 2

day_2/part_1.php

@@ -0,0 +1,23 @@
+<?php
+
+$instructions = explode("\n", file_get_contents('input.txt'));
+
+$position = 0;
+$depth = 0;
+
+foreach ($instructions as $instruction) {
+    [$movement, $value] = explode(' ', $instruction);
+    switch ($movement) {
+        case 'forward':
+            $position += $value;
+            break;
+        case 'up':
+            $depth -= $value;
+            break;
+        case 'down':
+            $depth += $value;
+            break;
+    }
+}
+
+echo sprintf('horizontal position %s × depth %s = %s', $position, $depth, $position * $depth);

day_2/part_2.php

@@ -0,0 +1,25 @@
+<?php
+
+$instructions = explode("\n", file_get_contents('input.txt'));
+
+$position = 0;
+$depth = 0;
+$aim = 0;
+
+foreach ($instructions as $instruction) {
+    [$movement, $value] = explode(' ', $instruction);
+    switch ($movement) {
+        case 'forward':
+            $position += $value;
+            $depth += $aim * $value;
+            break;
+        case 'up':
+            $aim -= $value;
+            break;
+        case 'down':
+            $aim += $value;
+            break;
+    }
+}
+
+echo sprintf('horizontal position %s × depth %s = %s', $position, $depth, $position * $depth);