# [94. Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)

## 题目


Given a binary tree, return the inorder traversal of its nodes' values.



**Example**:

```

Input: [1,null,2,3]
   1
    \
     2
    /
   3

Output: [1,3,2]

```


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




 

## 题目大意

中根遍历一颗树。

## 解题思路

递归的实现方法，见代码。





## 代码

```go

package leetcode

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func inorderTraversal(root *TreeNode) []int {
	var result []int
	inorder(root, &result)
	return result
}

func inorder(root *TreeNode, output *[]int) {
	if root != nil {
		inorder(root.Left, output)
		*output = append(*output, root.Val)
		inorder(root.Right, output)
	}
}

```