剑指offer（17）

输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）

先判断是否为空，递归判断左右子树是否是给定树的子结构。

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def HasSubtree(self, pRoot1, pRoot2):
        # write code here
        if ((pRoot1 == None) or (pRoot2 == None)):
            return False
        return self.Judgement(pRoot1, pRoot2) or self.HasSubtree(pRoot1.left, pRoot2) or self.HasSubtree(pRoot1.right, pRoot2)
    def Judgement(self,pRoot1,pRoot2):
        if pRoot2 == None:
            return True
        elif pRoot1 == None or pRoot1.val != pRoot2.val:
            return False
        else:
            return self.Judgement(pRoot1.left, pRoot2.left) and self.Judgement(pRoot1.right, pRoot2.right)