Add solution #2620

Author: JoshCrozier

README.md

@@ -363,6 +363,7 @@
 2535|[Difference Between Element Sum and Digit Sum of an Array](./2535-difference-between-element-sum-and-digit-sum-of-an-array.js)|Easy|
 2618|[Check if Object Instance of Class](./2618-check-if-object-instance-of-class.js)|Medium|
 2619|[Array Prototype Last](./2619-array-prototype-last.js)|Easy|
+2620|[Counter](./2620-counter.js)|Easy|
 2629|[Function Composition](./2629-function-composition.js)|Easy|
 3392|[Count Subarrays of Length Three With a Condition](./3392-count-subarrays-of-length-three-with-a-condition.js)|Easy|
 3396|[Minimum Number of Operations to Make Elements in Array Distinct](./3396-minimum-number-of-operations-to-make-elements-in-array-distinct.js)|Easy|

solutions/2620-counter.js

@@ -0,0 +1,18 @@
+/**
+ * 2620. Counter
+ * https://leetcode.com/problems/counter/
+ * Difficulty: Easy
+ *
+ * Given an integer n, return a counter function. This counter function initially
+ * returns n and then returns 1 more than the previous value every subsequent
+ * time it is called (n, n + 1, n + 2, etc).
+ */
+
+/**
+ * @param {number} n
+ * @return {Function} counter
+ */
+var createCounter = function(n) {
+  let count = n;
+  return () => count++;
+};