Given two binary trees, write a function to check if they are equal or not.
Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
递归比较两棵的根节点值是否相同和子树是否相同，实现为深度优先搜索。
# 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 is None and q is None: return True elif p is None or q is None: return False else: return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)