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

medium/find_elements_in_a_contaminated_binary_tree.py

@@ -0,0 +1,32 @@
+# 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
+