Add solution #954

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,039 LeetCode solutions in JavaScript
+# 1,040 LeetCode solutions in JavaScript
 
 [https://leetcode.com/](https://leetcode.com/)
 
@@ -763,6 +763,7 @@
 951|[Flip Equivalent Binary Trees](./solutions/0951-flip-equivalent-binary-trees.js)|Medium|
 952|[Largest Component Size by Common Factor](./solutions/0952-largest-component-size-by-common-factor.js)|Hard|
 953|[Verifying an Alien Dictionary](./solutions/0953-verifying-an-alien-dictionary.js)|Easy|
+954|[Array of Doubled Pairs](./solutions/0954-array-of-doubled-pairs.js)|Medium|
 966|[Vowel Spellchecker](./solutions/0966-vowel-spellchecker.js)|Medium|
 970|[Powerful Integers](./solutions/0970-powerful-integers.js)|Easy|
 976|[Largest Perimeter Triangle](./solutions/0976-largest-perimeter-triangle.js)|Easy|

solutions/0954-array-of-doubled-pairs.js

@@ -0,0 +1,30 @@
+/**
+ * 954. Array of Doubled Pairs
+ * https://leetcode.com/problems/array-of-doubled-pairs/
+ * Difficulty: Medium
+ *
+ * Given an integer array of even length arr, return true if it is possible to reorder arr such
+ * that arr[2 * i + 1] = 2 * arr[2 * i] for every 0 <= i < len(arr) / 2, or false otherwise.
+ */
+
+/**
+ * @param {number[]} arr
+ * @return {boolean}
+ */
+var canReorderDoubled = function(arr) {
+  const map = new Map();
+  arr.sort((a, b) => Math.abs(a) - Math.abs(b));
+
+  for (const num of arr) {
+    map.set(num, (map.get(num) || 0) + 1);
+  }
+  for (const num of arr) {
+    if (map.get(num) === 0) continue;
+    if (!map.has(2 * num) || map.get(2 * num) === 0) return false;
+
+    map.set(num, map.get(num) - 1);
+    map.set(2 * num, map.get(2 * num) - 1);
+  }
+
+  return true;
+};