Add solution #543

Author: JoshCrozier

README.md

@@ -318,6 +318,7 @@
 521|[Longest Uncommon Subsequence I](./0521-longest-uncommon-subsequence-i.js)|Easy|
 541|[Reverse String II](./0541-reverse-string-ii.js)|Easy|
 542|[01 Matrix](./0542-01-matrix.js)|Medium|
+543|[Diameter of Binary Tree](./0543-diameter-of-binary-tree.js)|Easy|
 547|[Number of Provinces](./0547-number-of-provinces.js)|Medium|
 551|[Student Attendance Record I](./0551-student-attendance-record-i.js)|Easy|
 557|[Reverse Words in a String III](./0557-reverse-words-in-a-string-iii.js)|Easy|

solutions/0543-diameter-of-binary-tree.js

@@ -0,0 +1,38 @@
+/**
+ * 543. Diameter of Binary Tree
+ * https://leetcode.com/problems/diameter-of-binary-tree/
+ * Difficulty: Easy
+ *
+ * Given the root of a binary tree, return the length of the diameter of the tree.
+ *
+ * The diameter of a binary tree is the length of the longest path between any two nodes in a
+ * tree. This path may or may not pass through the root.
+ *
+ * The length of a path between two nodes is represented by the number of edges between them.
+ */
+
+/**
+ * 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 diameterOfBinaryTree = function(root) {
+  let result = 0;
+  maxDepth(root);
+  return result;
+
+  function maxDepth(node) {
+    if (!node) return 0;
+    const left = maxDepth(node.left);
+    const right = maxDepth(node.right);
+    result = Math.max(result, left + right);
+    return Math.max(left, right) + 1;
+  }
+};