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# 1261. Find Elements in a Contaminated Binary Tree

<https://leetcode.com/problems/find-elements-in-a-contaminated-binary-tree>

## Description

Given a binary tree with the following rules:

1. `root.val == 0`
2. If `treeNode.val == x` and `treeNode.left != null`, then `treeNode.left.val == 2 * x + 1`
3. If `treeNode.val == x` and `treeNode.right != null`, then `treeNode.right.val == 2 * x + 2`

Now the binary tree is contaminated, which means all `treeNode.val` have been changed to `-1`.

Implement the `FindElements` class:

* `FindElements(TreeNode* root)` Initializes the object with a contaminated binary tree and recovers it.
* `bool find(int target)` Returns `true` if the `target` value exists in the recovered binary tree.

**Example 1:**

![](https://assets.leetcode.com/uploads/2019/11/06/untitled-diagram-4-1.jpg)

```
**Input**
["FindElements","find","find"]
[[[-1,null,-1]],[1],[2]]
**Output**
[null,false,true]
**Explanation**
FindElements findElements = new FindElements([-1,null,-1]); 
findElements.find(1); // return False 
findElements.find(2); // return True 
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2019/11/06/untitled-diagram-4.jpg)

```
**Input**
["FindElements","find","find","find"]
[[[-1,-1,-1,-1,-1]],[1],[3],[5]]
**Output**
[null,true,true,false]
**Explanation**
FindElements findElements = new FindElements([-1,-1,-1,-1,-1]);
findElements.find(1); // return True
findElements.find(3); // return True
findElements.find(5); // return False
```

**Example 3:**

![](https://assets.leetcode.com/uploads/2019/11/07/untitled-diagram-4-1-1.jpg)

```
**Input**
["FindElements","find","find","find","find"]
[[[-1,null,-1,-1,null,-1]],[2],[3],[4],[5]]
**Output**
[null,true,false,false,true]
**Explanation**
FindElements findElements = new FindElements([-1,null,-1,-1,null,-1]);
findElements.find(2); // return True
findElements.find(3); // return False
findElements.find(4); // return False
findElements.find(5); // return True
```

**Constraints:**

* `TreeNode.val == -1`
* The height of the binary tree is less than or equal to `20`
* The total number of nodes is between `[1, 104]`
* Total calls of `find()` is between `[1, 104]`
* `0 <= target <= 106`

## ac

```java
```


---

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