```
def findTarget(self, root, k):
a = set()
self.f = False
def dfs(root, k):
if not root:
return
if root.val not in a:
a.add(k - root.val)
else:
self.f = True
dfs(root.left, k)
dfs(root.right, k)
dfs(root, k)
return self.f
```