✨ Commence le jour 9

day_9/part_1.php

@@ -0,0 +1,90 @@
+<?php
+
+$instructions = explode("\n", file_get_contents('./input.txt'));
+
+$h = [0,0];
+$t = [0,0];
+$places = ["0-0"];
+
+$grid = [
+    ['#'],
+];
+
+foreach ($instructions as $instruction) {
+    [$direction, $length] = explode(' ', $instruction);
+    for ($i = 0; $i < $length; $i++) {
+        $newH = $h;
+
+        switch ($direction) {
+            case 'U':
+                $newH[0]++;
+                break;
+            case 'R':
+                $newH[1]++;
+                break;
+            case 'D':
+                $newH[0]--;
+                break;
+            case 'L':
+                $newH[1]--;
+                break;
+        }
+
+        if (areTooFarAway($newH, $t)) {
+            $t = $h;
+            $places[] = implode('-', $h);
+            $grid[$h[0]][$h[1]] = '#';
+        }
+
+        $h = $newH;
+    }
+}
+
+displayGrid($grid);
+
+echo count(array_unique($places));
+
+/**
+ * @param int[] $x
+ * @param int[] $y
+ *
+ * @return bool
+ */
+function areTooFarAway($x, $y): bool
+{
+    for ($i = $x[0] - 1, $l = $x[0] + 1; $i <= $l; $i++) {
+        for ($j = $x[1] - 1, $m = $x[1] + 1; $j <= $m; $j++) {
+            if ($y[0] === $i && $y[1] === $j) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+/**
+ * @param array $grid
+ *
+ * @return void
+ */
+function displayGrid($grid): void
+{
+    $maxRow = 0;
+    foreach ($grid as $item) {
+        $maxRow = max($maxRow, count($item));
+    }
+
+    $grid = array_reverse($grid);
+
+    foreach ($grid as $iValue) {
+        for ($j = 0; $j <= $maxRow; $j++) {
+            if (isset($iValue[$j])) {
+                echo $iValue[$j];
+            } else {
+                echo '.';
+            }
+        }
+        echo "\n";
+    }
+}