Add solution #219

Author: JoshCrozier

Diff for: README.md

@@ -31,6 +31,7 @@
 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|
+219|[Contains Duplicate II](./0219-contains-duplicate-ii.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|

Diff for: solutions/0219-contains-duplicate-ii.js

@@ -0,0 +1,27 @@
+/**
+ * 219. Contains Duplicate II
+ * https://leetcode.com/problems/contains-duplicate-ii/
+ * Difficulty: Easy
+ *
+ * Given an integer array `nums` and an integer `k`, return `true` if there are
+ * two distinct indices `i` and `j` in the array such that `nums[i] == nums[j]`
+ * and `abs(i - j) <= k`.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {boolean}
+ */
+var containsNearbyDuplicate = function(nums, k) {
+  const map = new Map();
+
+  for (let i = 0; i < nums.length; i++) {
+    if (Math.abs(i - map.get(nums[i])) <= k) {
+      return true;
+    }
+    map.set(nums[i], i);
+  }
+
+  return false;
+};