'''
给定两个二叉树，编写一个函数来检验它们是否相同。

如果两个树在结构上相同，并且节点具有相同的值，则认为它们是相同的。

示例 1:

输入:       1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

输出: true
示例 2:

输入:      1          1
          /           \
         2             2

        [1,2],     [1,null,2]

输出: false
示例 3:

输入:       1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

输出: false

'''
#递归
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """
        if p == None and q == None:
            return True
        elif p == None or q == None:
            return False
        elif p.val == q.val:
            return self.isSameTree(p.left,q.left) and self.isSameTree(p.right,q.right)
        else:
            return False
            
#前序遍历
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """
        def fun(root):
            ret,stack = [],[root]
            while stack:
                temp = stack.pop()
                if temp:
                    ret.append(str(temp.val))
                    stack.append(temp.right)
                    stack.append(temp.left)
                else:
                    ret.append("#")
            return ret
        a = fun(p)
        b = fun(q)
        if a == b:
            return True
        else:
            return False


        

