LeetCode:Same Tree

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.

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

class Solution:
    # @param p, a tree node
    # @param q, a tree node
    # @return a boolean
    def isSameTree(self, p, q):
        if (p==None and q==None): #如果都是空，是相同的
            return True
        elif ((p!=None and q==None) or (p==None and q!=None)):#如果有一个是空，另一个不是空，则不同
            return False
        else: #进入此条件的是两个都不为空，所以必有值和左右节点，虽然有可能是空，然后递归
            return((p.val==q.val and self.isSameTree(p.left,q.left) and self.isSameTree(p.right, q.right)))