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

Given a binary tree, remove the nodes in which there is only 1 child, so that the binary tree is a full binary tree.

So leaf nodes with no children should be kept, and nodes with 2 children should be kept as well.

Here’s a starting point:

```
from collections import deque
class Node(object):
def __init__(self, value, left=None, right=None):
self.left = left
self.right = right
self.value = value
def __str__(self):
q = deque()
q.append(self)
result = ''
while len(q):
num = len(q)
while num > 0:
n = q.popleft()
result += str(n.value)
if n.left:
q.append(n.left)
if n.right:
q.append(n.right)
num = num - 1
if len(q):
result += "\n"
return result
def fullBinaryTree(node):
# Fill this in.
# Given this tree:
# 1
# / \
# 2 3
# / / \
# 0 9 4
# We want a tree like:
# 1
# / \
# 0 3
# / \
# 9 4
tree = Node(1)
tree.left = Node(2)
tree.right = Node(3)
tree.right.right = Node(4)
tree.right.left = Node(9)
tree.left.left = Node(0)
print fullBinaryTree(tree)
# 1
# 03
# 94
```