Add solution #594

Author: JoshCrozier

README.md

@@ -234,6 +234,7 @@
 566|[Reshape the Matrix](./0566-reshape-the-matrix.js)|Easy|
 567|[Permutation in String](./0567-permutation-in-string.js)|Medium|
 575|[Distribute Candies](./0575-distribute-candies.js)|Easy|
+594|[Longest Harmonious Subsequence](./0594-longest-harmonious-subsequence.js)|Easy|
 599|[Minimum Index Sum of Two Lists](./0599-minimum-index-sum-of-two-lists.js)|Easy|
 605|[Can Place Flowers](./0605-can-place-flowers.js)|Easy|
 606|[Construct String from Binary Tree](./0606-construct-string-from-binary-tree.js)|Easy|

solutions/0594-longest-harmonious-subsequence.js

@@ -0,0 +1,24 @@
+/**
+ * 594. Longest Harmonious Subsequence
+ * https://leetcode.com/problems/longest-harmonious-subsequence/
+ * Difficulty: Easy
+ *
+ * We define a harmonious array as an array where the difference between its maximum
+ * value and its minimum value is exactly 1.
+ *
+ * Given an integer array nums, return the length of its longest harmonious subsequence
+ * among all its possible subsequences.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findLHS = function(nums) {
+  const map = new Map();
+  nums.forEach(n => map.set(n, (map.get(n) ?? 0) + 1));
+
+  return Array.from(map).reduce((result, [n, count]) => {
+    return map.has(n + 1) ? Math.max(result, count + map.get(n + 1)) : result;
+  }, 0);
+};