Add solution #1331

Author: JoshCrozier

README.md

@@ -230,6 +230,7 @@
 1318|[Minimum Flips to Make a OR b Equal to c](./1318-minimum-flips-to-make-a-or-b-equal-to-c.js)|Medium|
 1323|[Maximum 69 Number](./1323-maximum-69-number.js)|Easy|
 1324|[Print Words Vertically](./1324-print-words-vertically.js)|Medium|
+1331|[Rank Transform of an Array](./1331-rank-transform-of-an-array.js)|Easy|
 1332|[Remove Palindromic Subsequences](./1332-remove-palindromic-subsequences.js)|Easy|
 1333|[Filter Restaurants by Vegan-Friendly, Price and Distance](./1333-filter-restaurants-by-vegan-friendly-price-and-distance.js)|Medium|
 1342|[Number of Steps to Reduce a Number to Zero](./1342-number-of-steps-to-reduce-a-number-to-zero.js)|Easy|

solutions/1331-rank-transform-of-an-array.js

@@ -0,0 +1,25 @@
+/**
+ * 1331. Rank Transform of an Array
+ * https://leetcode.com/problems/rank-transform-of-an-array/
+ * Difficulty: Easy
+ *
+ * Given an array of integers arr, replace each element with its rank.
+ *
+ * The rank represents how large the element is. The rank has the following rules:
+ * - Rank is an integer starting from 1.
+ * - The larger the element, the larger the rank. If two elements are equal, their
+ *   rank must be the same.
+ * - Rank should be as small as possible.
+ */
+
+/**
+ * @param {number[]} arr
+ * @return {number[]}
+ */
+var arrayRankTransform = function(arr) {
+  const ranks = [...new Set(arr)]
+    .sort((a, b) => a - b)
+    .reduce((map, value, index) => map.set(value, index + 1), new Map());
+
+  return arr.map(rank => ranks.get(rank));
+};