add q1365 draft

Author: rishabh1403

1301-1400/1365-how-many-numbers-smaller-than-current-number.js

@@ -0,0 +1,13 @@
+/*
+Author :- Rishabh Jain <contact@rishabh1403.com>
+Solution for :- https://leetcode.com/problems/missing-number/
+blog for this code :- https://rishabh1403.com/posts/coding/leetcode/2020/03/leetcode-missing-number
+youtube video :- https://youtu.be/I6AUMvi13fc
+*/
+
+
+var smallerNumbersThanCurrent = function (nums) {
+  const sorted = [...nums].sort((a, b) => a - b);
+
+  return nums.map(num => sorted.indexOf(num));
+};