給定兩個二叉樹，編寫一個函式來檢驗它們是否相同。

如果兩個樹在結構上相同，並且節點具有相同的值，則認為它們是相同的。

示例 1:

輸入:       1         1
          / \       / \
         2   3     2   3

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

輸出: true

示例 2:

輸入:      1          1
          /           \
         2             2

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

輸出: false

示例 3:

輸入:       1         1
          / \       / \
         2   1     1   2

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

輸出: false

#!/usr/bin/python3
# -*- coding: utf-8 -*-
# @Time: 2018/7/26
# @Author: xfLi
# The file...

class TreeNode:
    def __init__(self, x=None, left = None, right = None):
        self.val = x
        self.left = left
        self.right = right

def isSameTree(p, q):
    """
    :type p: TreeNode
    :type q: TreeNode
    :rtype: bool
    """
    if p == None and q == None: # 二叉樹皆為空，遞迴邊界，兩者皆為空返回真
        return True

    if p == None or q == None:
        return False

    if p.val == q.val:
        return isSameTree(p.left, q.left) and isSameTree(p.right, q.right)
    else:
        return False

if __name__ == '__main__':
    p = TreeNode(x=1, left=TreeNode(3), right=TreeNode(3))
    q = TreeNode(x=1, left=TreeNode(3), right=TreeNode(3))
    result = isSameTree(p,q)
    print(result)