Add solution #116

Author: JoshCrozier

README.md

@@ -54,6 +54,7 @@
 104|[Maximum Depth of Binary Tree](./0104-maximum-depth-of-binary-tree.js)|Easy|
 111|[Minimum Depth of Binary Tree](./0111-minimum-depth-of-binary-tree.js)|Easy|
 112|[Path Sum](./0112-path-sum.js)|Easy|
+116|[Populating Next Right Pointers in Each Node](./0116-populating-next-right-pointers-in-each-node.js)|Medium|
 118|[Pascal's Triangle](./0118-pascals-triangle.js)|Easy|
 119|[Pascal's Triangle II](./0119-pascals-triangle-ii.js)|Easy|
 121|[Best Time to Buy and Sell Stock](./0121-best-time-to-buy-and-sell-stock.js)|Easy|

solutions/0116-populating-next-right-pointers-in-each-node.js

@@ -0,0 +1,50 @@
+/**
+ * 116. Populating Next Right Pointers in Each Node
+ * https://leetcode.com/problems/populating-next-right-pointers-in-each-node/
+ * Difficulty: Medium
+ *
+ * You are given a perfect binary tree where all leaves are on the same level, and
+ * every parent has two children. The binary tree has the following definition:
+ *
+ * Populate each next pointer to point to its next right node. If there is no next
+ * right node, the next pointer should be set to NULL.
+ *
+ * Initially, all next pointers are set to NULL.
+ */
+
+/**
+ * // Definition for a Node.
+ * function Node(val, left, right, next) {
+ *    this.val = val === undefined ? null : val;
+ *    this.left = left === undefined ? null : left;
+ *    this.right = right === undefined ? null : right;
+ *    this.next = next === undefined ? null : next;
+ * };
+ */
+
+/**
+ * @param {Node} root
+ * @return {Node}
+ */
+var connect = function(root) {
+  const order = [];
+  traverse(order, root);
+  for (let level of order) {
+    for (let i = 0; i < level.length - 1; i++) {
+      level[i].next = level[i + 1];
+    }
+  }
+  return root;
+};
+
+function traverse(order, node, level = 0) {
+  if (!node) {
+    return [];
+  }
+
+  order[level] = order[level] || [];
+  order[level].push(node);
+
+  traverse(order, node.left, level + 1);
+  traverse(order, node.right, level + 1);
+}