Hi, here’s your problem today. This problem was recently asked by Facebook:

Given two binary trees that are duplicates of one another, and given a node in one tree, find that correponding node in the second tree.

For instance, in the tree below, we’re looking for Node #4.

For this problem, you can assume that:

- There can be duplicate values in the tree (so comparing node1.value == node2.value isn’t going to work).

Can you solve this both recursively and iteratively?

```
class Node:
def __init__(self, val):
self.val = val
self.left = None
self.right = None
def findNode(a, b, node):
# Fill this in.
# 1
# / \
#2 3
# / \
# 4* 5
a = Node(1)
a.left = Node(2)
a.right = Node(3)
a.right.left = Node(4)
a.right.right = Node(5)
b = Node(1)
b.left = Node(2)
b.right = Node(3)
b.right.left = Node(4)
b.right.right = Node(5)
print(findNode(a, b, a.right.left))
# 4
```