public class FindElements
extends Object
1261 - Find Elements in a Contaminated Binary Tree\.
Medium
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:**
**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:**
**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:**
**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