题目链接：https://leetcode-cn.com/problems/shu-de-zi-jie-gou-lcof/
难度：中等

描述：
输入两棵二叉树A和B，判断B是不是A的子结构。(约定空树不是任意一个树的子结构)
B是A的子结构， 即 A中有出现和B相同的结构和节点值。

题解

  1. # Definition for a binary tree node.
  2. # class TreeNode:
  3. #     def __init__(self, x):
  4. #         self.val = x
  5. #         self.left = None
  6. #         self.right = None
  8. class Solution:
  9.     def isSubStructure(self, A: TreeNode, B: TreeNode) -> bool:
  10.         def recursion(A, B):
  11.             if B is None:
  12.                 return True
  13.             if A is None or A.val != B.val:
  14.                 return False
  15.             return recursion(A.left, B.left) and recursion(A.right, B.right)
  17.         if A is None or B is None:
  18.             return False
  19.         else:
  20.             return recursion(A, B) or self.isSubStructure(A.left, B) or self.isSubStructure(A.right, B)