## Description #

Difficulty: **简单**

Related Topics: Stack, Tree, Depth-First Search, Binary Tree

Given the `root`

of a binary tree, return *the inorder traversal of its nodes’ values*.

**Example 1:**

```
Input: root = [1,null,2,3]
Output: [1,3,2]
```

**Example 2:**

```
Input: root = []
Output: []
```

**Example 3:**

```
Input: root = [1]
Output: [1]
```

**Constraints:**

- The number of nodes in the tree is in the range
`[0, 100]`

. `-100 <= Node.val <= 100`

**Follow up:** Recursive solution is trivial, could you do it iteratively?

## Solution #

Language: **Go**