Add solution #217

Author: JoshCrozier

README.md

@@ -30,6 +30,7 @@
 67|[Add Binary](./0067-add-binary.js)|Easy|
 151|[Reverse Words in a String](./0151-reverse-words-in-a-string.js)|Medium|
 152|[Maximum Product Subarray](./0152-maximum-product-subarray.js)|Medium|
+217|[Contains Duplicate](./0217-contains-duplicate.js)|Easy|
 226|[Invert Binary Tree](./0226-invert-binary-tree.js)|Easy|
 263|[Ugly Number](./0263-ugly-number.js)|Easy|
 264|[Ugly Number II](./0264-ugly-number-ii.js)|Medium|

solutions/0217-contains-duplicate.js

@@ -0,0 +1,16 @@
+/**
+ * 217. Contains Duplicate
+ * https://leetcode.com/problems/contains-duplicate/
+ * Difficulty: Easy
+ *
+ * Given an integer array `nums`, return `true` if any value appears at least
+ * twice in the array, and return `false` if every element is distinct.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function(nums) {
+  return new Set(nums).size !== nums.length;
+};