🚧 Commence le jour 12

day_12/part_1.php

@@ -0,0 +1,71 @@
+<?php
+
+$instructions = explode("\n", file_get_contents('input.txt'));
+
+const NORTH = 'N';
+const SOUTH = 'S';
+const EAST = 'E';
+const WEST = 'W';
+const LEFT = 'L';
+const RIGHT = 'R';
+const FORWARD = 'F';
+
+$facings = [NORTH, EAST, SOUTH, WEST];
+
+$facing = EAST;
+$east = 0;
+$north = 0;
+
+function doingInstruction($direction, $value)
+{
+    global $north, $east, $facings, $facing;
+    switch ($direction) {
+        case NORTH:
+            $north += $value;
+            break;
+        case SOUTH:
+            $north -= $value;
+            break;
+        case EAST:
+            $east += $value;
+            break;
+        case WEST:
+            $east -= $value;
+            break;
+        case LEFT:
+            $turns = $value / 90;
+            $array_position = array_search($facing, $facings);
+            $array_max = 4;
+            for ($i = $turns; $i > 0; $i--) {
+                $array_position--;
+                if ($array_position === -1) {
+                    $array_position = $array_max - 1;
+                }
+            }
+            $facing = $facings[$array_position];
+            break;
+        case RIGHT:
+            $turns = $value / 90;
+            $array_position = array_search($facing, $facings);
+            $array_max = 4;
+            for ($i = 0; $i < $turns; $i++) {
+                $array_position++;
+                if ($array_position === $array_max) {
+                    $array_position = 0;
+                }
+            }
+            $facing = $facings[$array_position];
+            break;
+        case FORWARD:
+            doingInstruction($facing, (int)$value);
+            break;
+    }
+}
+
+foreach ($instructions as $instruction) {
+    $direction = $instruction[0];
+    $value = (int)substr($instruction, 1);
+    doingInstruction($direction, $value);
+}
+
+echo abs($east) + abs($north);