Add solution #1161

Author: JoshCrozier

README.md

@@ -348,6 +348,7 @@
 1103|[Distribute Candies to People](./1103-distribute-candies-to-people.js)|Easy|
 1108|[Defanging an IP Address](./1108-defanging-an-ip-address.js)|Easy|
 1122|[Relative Sort Array](./1122-relative-sort-array.js)|Easy|
+1161|[Maximum Level Sum of a Binary Tree](./1161-maximum-level-sum-of-a-binary-tree.js)|Medium|
 1189|[Maximum Number of Balloons](./1189-maximum-number-of-balloons.js)|Easy|
 1200|[Minimum Absolute Difference](./1200-minimum-absolute-difference.js)|Easy|
 1206|[Design Skiplist](./1206-design-skiplist.js)|Hard|

solutions/1161-maximum-level-sum-of-a-binary-tree.js

@@ -0,0 +1,42 @@
+/**
+ * 1161. Maximum Level Sum of a Binary Tree
+ * https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, the level of its root is 1, the level of its
+ * children is 2, and so on.
+ *
+ * Return the smallest level x such that the sum of all the values of nodes at
+ * level x is maximal.
+ */
+
+/**
+ * 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 maxLevelSum = function(root) {
+  const sums = [-Infinity];
+
+  traverse(root, 1);
+
+  return sums.indexOf(Math.max(...sums));
+
+  function traverse(node, depth) {
+    if (!node) return;
+    if (sums[depth] === undefined) {
+      sums.push(node.val);
+    } else {
+      sums[depth] += node.val;
+    }
+    traverse(node.left, depth + 1);
+    traverse(node.right, depth + 1);
+  }
+};