Given a binary tree with the following rules:
- root.val == 0
- If treeNode.val == x and treeNode.left != null, then treeNode.left.val == 2 x + 1
- 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.