Initial data commit

Task/Factorial/PHP/factorial-1.php

@@ -0,0 +1,14 @@
+<?php
+function factorial($n) {
+  if ($n < 0) {
+    return 0;
+  }
+
+  $factorial = 1;
+  for ($i = $n; $i >= 1; $i--) {
+    $factorial = $factorial * $i;
+  }
+
+  return $factorial;
+}
+?>

Task/Factorial/PHP/factorial-2.php

@@ -0,0 +1,15 @@
+<?php
+function factorial($n) {
+  if ($n < 0) {
+    return 0;
+  }
+
+  if ($n == 0) {
+    return 1;
+  }
+
+  else {
+    return $n * factorial($n-1);
+  }
+}
+?>

Task/Factorial/PHP/factorial-3.php

@@ -0,0 +1,3 @@
+<?php
+function factorial($n) { return $n == 0 ? 1 : array_product(range(1, $n)); }
+?>

Task/Factorial/PHP/factorial-4.php

@@ -0,0 +1 @@
+gmp_fact($n)