[Leetcode] 617. Merge Two Binary Trees

Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not.

You need to merge them into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of new tree.

就是将两棵树各节点相加。 python类里面方法递归调用的时候出现了点问题，要在前面加self.，不然总是报错global name “mergeTrees”未定义

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def mergeTrees(self, t1, t2):        """        :type t1: TreeNode        :type t2: TreeNode        :rtype: TreeNode        """        if not t1:            return t2        if not t2:            return t1                t1.val += t2.val        t1.left =  self.mergeTrees(t1.left,t2.left)        t1.right = self.mergeTrees(t1.right,t2.right)        return t1