Easy
合并两个二叉树，我们想到可以使用相同的方式同时遍历两棵树
需要处理一下，一个节点为空，另一个节点有值的情况即可。这边选择使用DFS方式遍历
以上，尝试写一下代码，AC！
python3
class Solution:
def mergeTrees(self, t1: TreeNode, t2: TreeNode) -> TreeNode:
def dfs(node1, node2):
if node1 is None and node2 is None:
return None
val = 0
if node1 is not None:
val += node1.val
if node2 is not None:
val += node2.val
node = TreeNode(val)
node1_left = node1.left if node1 is not None else None
node2_left = node2.left if node2 is not None else None
node1_right = node1.right if node1 is not None else None
node2_right = node2.right if node2 is not None else None
node.left = dfs(node1_left, node2_left)
node.right = dfs(node1_right, node2_right)
return node
return dfs(t1,t2)