Add solution #637

Author: JoshCrozier

README.md

@@ -419,6 +419,7 @@
 617|[Merge Two Binary Trees](./0617-merge-two-binary-trees.js)|Easy|
 621|[Task Scheduler](./0621-task-scheduler.js)|Medium|
 628|[Maximum Product of Three Numbers](./0628-maximum-product-of-three-numbers.js)|Easy|
+637|[Average of Levels in Binary Tree](./0637-average-of-levels-in-binary-tree.js)|Easy|
 643|[Maximum Average Subarray I](./0643-maximum-average-subarray-i.js)|Easy|
 645|[Set Mismatch](./0645-set-mismatch.js)|Medium|
 648|[Replace Words](./0648-replace-words.js)|Medium|

solutions/0637-average-of-levels-in-binary-tree.js

@@ -0,0 +1,41 @@
+/**
+ * 637. Average of Levels in Binary Tree
+ * https://leetcode.com/problems/average-of-levels-in-binary-tree/
+ * Difficulty: Easy
+ *
+ * Given the root of a binary tree, return the average value of the nodes on each level in the
+ * form of an array. Answers within 10-5 of the actual answer will be accepted.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+var averageOfLevels = function(root) {
+  const result = [];
+  const queue = [root];
+
+  while (queue.length) {
+    const level = queue.length;
+    let sum = 0;
+
+    for (let i = 0; i < level; i++) {
+      const node = queue.shift();
+      sum += node.val;
+      if (node.left) queue.push(node.left);
+      if (node.right) queue.push(node.right);
+    }
+
+    result.push(sum / level);
+  }
+
+  return result;
+};