题解 | #合并二叉树#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param t1 TreeNode类 
# @param t2 TreeNode类 
# @return TreeNode类
#
class Solution:
    def merge(self,t1: TreeNode, t2: TreeNode):
        t1.val += t2.val
        if t1.left is None and t2.left:
            # t1没左t2有左
            t1.left = t2.left
        elif t1.left and t2.left:
            # 都有左，进入递归
            self.merge(t1.left, t2.left)
        # 都没左，不动就行

        # 右边同理
        if t1.right is None and t2.right:
            t1.right = t2.right
        elif t1.right and t2.right:
            self.merge(t1.right, t2.right)

    def mergeTrees(self,t1: TreeNode, t2: TreeNode):
        if t1 is None:
            return t2
        if t2 is None:
            return t1
        self.merge(t1,t2)
        return t1