# 0951. Flip Equivalent Binary Trees

https://leetcode.com/problems/flip-equivalent-binary-trees

## Description

For a binary tree **T**, we can define a **flip operation** as follows: choose any node, and swap the left and right child subtrees.

A binary tree **X** is _flip equivalent_ to a binary tree **Y** if and only if we can make **X** equal to **Y** after some number of flip operations.

Given the roots of two binary trees `root1` and `root2`, return `true` if the two trees are flip equivelent or `false` otherwise.

**Example 1:**

![Flipped Trees Diagram](https://assets.leetcode.com/uploads/2018/11/29/tree_ex.png)

```
**Input:** root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7]
**Output:** true
**Explanation:** We flipped at nodes with values 1, 3, and 5.
```

**Example 2:**

```
**Input:** root1 = [], root2 = []
**Output:** true
```

**Example 3:**

```
**Input:** root1 = [], root2 = [1]
**Output:** false
```

**Example 4:**

```
**Input:** root1 = [0,null,1], root2 = []
**Output:** false
```

**Example 5:**

```
**Input:** root1 = [0,null,1], root2 = [0,1]
**Output:** true
```

**Constraints:**

* The number of nodes in each tree is in the range `[0, 100]`.
* Each tree will have **unique node values** in the range `[0, 99]`.

## ac

```java
```
