Added English README

Author: brenobaptista

leetcode/0543.Diameter-of-Binary-Tree/README.md

@@ -0,0 +1,31 @@
+# [543. Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/)
+
+## 题目
+
+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.
+
+**Example 1:**
+
+![https://assets.leetcode.com/uploads/2021/03/06/diamtree.jpg](https://assets.leetcode.com/uploads/2021/03/06/diamtree.jpg)
+
+```
+Input: root = [1,2,3,4,5]
+Output: 3
+Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
+```
+
+**Example 2:**
+
+```
+Input: root = [1,2]
+Output: 1
+```
+
+**Constraints:**
+
+- The number of nodes in the tree is in the range `[1, 104]`.
+- `-100 <= Node.val <= 100`