Add solution #104

Author: JoshCrozier

README.md

@@ -42,6 +42,7 @@
 88|[Merge Sorted Array](./0088-merge-sorted-array.js)|Easy|
 94|[Binary Tree Inorder Traversal](./0094-binary-tree-inorder-traversal.js)|Easy|
 102|[Binary Tree Level Order Traversal](./0102-binary-tree-level-order-traversal.js)|Medium|
+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|
 118|[Pascal's Triangle](./0118-pascals-triangle.js)|Easy|
 119|[Pascal's Triangle II](./0119-pascals-triangle-ii.js)|Easy|

solutions/0104-maximum-depth-of-binary-tree.js

@@ -0,0 +1,30 @@
+/**
+ * 104. Maximum Depth of Binary Tree
+ * https://leetcode.com/problems/maximum-depth-of-binary-tree/
+ * Difficulty: Easy
+ *
+ * Given the root of a binary tree, return its maximum depth.
+ *
+ * A binary tree's maximum depth is the number of nodes along the longest
+ * path from the root node down to the farthest leaf node.
+ */
+
+/**
+ * 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 maxDepth = function(root) {
+  if (!root) {
+    return 0;
+  }
+  const [left, right] = [root.left, root.right].map(maxDepth);
+  return 1 + Math.max(left, right);
+};