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

from typing import Optional, Set

class TreeNode:
  def __init__(self, val=0, left=None, right=None):
    self.val = val
    self.left = left
    self.right = right

class FindElements:
  r: Optional[TreeNode]
  s: Set[int]

  def __init__(self, root: Optional[TreeNode]):
    self.r = root
    self.s = set()
    if self.r is not None:
        self.s.add(0)
        self.recurse_init(self.r, 0)

  def recurse_init(self, curr: TreeNode, curr_val: int):
    if curr.left is not None:
      self.s.add(curr_val * 2 + 1)
      self.recurse_init(curr.left, curr_val * 2 + 1)
    if curr.right is not None:
      self.s.add(curr_val * 2 + 2)
      self.recurse_init(curr.right, curr_val * 2 + 2)

  def find(self, target: int) -> bool:
    return target in self.s