fix/ refactor

Author: nik-rev

13_factorial/solution/factorial-solution.js

@@ -6,9 +6,9 @@ const factorial = function(n) {
   if (/[-.]/.test(n + '')) return;
 
   // +n converts n to a number
-  if (+n === 0 || +n === 1) return 1;
+  if (+n === 0) return 1;
   return n * factorial(n - 1);
 };
 
 // Do not edit below this line
-module.exports = factorial;
+module.exports = factorial;