//递归法*前序遍历

classSolution:

defmergeTrees(self,root1: TreeNode,root2: TreeNode) -> TreeNode:

ifnot root1:return root2// 如果t1为空，合并之后就应该是t2

root1.left=self.mergeTrees(root1.left , root2.left)//左

root1.right=self.mergeTrees(root1.right , root2.right)//右

return root1//root1修改了结构和数值

classSolution:

defmergeTrees(self,root1: TreeNode,root2: TreeNode) -> TreeNode:

ifnot root1:return root2

ifnot root2:return root1

queue1= [root1]

queue2= [root2]

root= root1

while queue1and queue2:

root1= queue1.pop(0)

root2= queue2.pop(0)

root1.val+= root2.val

ifnot root1.left:# 如果树1左儿子不存在，则覆盖后树1的左儿子为树2的左儿子

root1.left= root2.left

elif root1.leftand root2.left:

queue1.append(root1.left)

queue2.append(root2.left)

ifnot root1.right:# 同理，处理右儿子

root1.right= root2.right

elif root1.rightand root2.right:

queue1.append(root1.right)

queue2.append(root2.right)

return root

Go：