text: class Solution:
      def findTarget(self, root, k):
          """
          :type root: TreeNode
          :type k: int
          :rtype: bool
          """
          
          """
          if k > root.val then scan all 
          if k < root.val then scan left
          """
          
          if root == None:
              return False
          stack = [root]
          
          comp = {}
          ans = False
  
          while len(stack) != 0:
              node = stack.pop(0)
              if k - node.val in comp:
                  ans = True
              comp[node.val] = True
              
              if node.left:
                  stack.append(node.left)
              if node.right:
                  stack.append(node.right)
          
          print(comp, ans)
  
          return ans
  