leetcode 94 给定一个二叉树的根节点 root ，返回它的中序遍历。

2021-07-14 305 阅读1分钟

给定一个二叉树的根节点 root ，返回它的中序遍历。

/**

Definition for a binary tree node.
public class TreeNode {
```
int val;
```
```
TreeNode left;
```
```
TreeNode right;
```
```
TreeNode() {}
```
```
TreeNode(int val) { this.val = val; }
```

TreeNode(int val, TreeNode left, TreeNode right) {

```
    this.val = val;
```
```
    this.left = left;
```
```
    this.right = right;
```
```
}
```
} */ class Solution { public List inorderTraversal(TreeNode root) { List res = new ArrayList(); inorder(root,res); return res; }

public void inorder(TreeNode root,List res){ if( root == null){ return; } inorder(root.left,res); res.add(root.val); inorder(root.right,res); } }