13th day both parts

13/part1.php

@@ -0,0 +1,44 @@
+<?php
+
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$coordinates = [];
+$folds = [];
+foreach ($input as $line) {
+    if (strstr($line, 'fold')) {
+        preg_match('#fold along ([x|y])=(\d*)#', $line, $found);
+        $folds[] = [$found[1], (int)$found[2]];
+    } else {
+        $point = explode(',', $line);
+        $coordinates[] = $point;
+    }
+}
+foreach ($folds as $fold) {
+    foreach ($coordinates as &$point) {
+        if ($fold[0] == 'x') {
+            if ($point[0] > $fold[1]) {
+                $point[0] = $fold[1] * 2 - $point[0];
+            }
+        }
+        if ($fold[0] == 'y') {
+            if ($point[1] > $fold[1]) {
+                $point[1] = $fold[1] * 2 - $point[1];
+            }
+        }
+    }
+    $coordinates = points_unique($coordinates);
+    echo count($coordinates); //751
+    die();
+}
+
+function points_unique($coordinates)
+{
+    $tmp = [];
+    $newCoordinates = [];
+    foreach ($coordinates as $point) {
+        if (!isset($tmp[implode(',', $point)])) {
+            $newCoordinates[] = $point;
+            $tmp[implode(',', $point)] = 1;
+        }
+    }
+    return $newCoordinates;
+}