Subtree of Another Tree.md

Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.

Example 1:
Given tree s:

     3
    / \
   4   5
  / \
 1   2
Given tree t:
   4 
  / \
 1   2
Return true, because t has the same structure and node values with a subtree of s.
Example 2:
Given tree s:

     3
    / \
   4   5
  / \
 1   2
    /
   0
Given tree t:
   4
  / \
 1   2
Return false.

My code:

# 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 isSubtree(self, s, t):
        """
        :type s: TreeNode
        :type t: TreeNode
        :rtype: bool
        """
        label=self.isSubtree2(s,t,0)
        return label
    def isSubtree2(self,s,t,mode):
        if s==None and t==None:
            return True
        if s==None and t!=None:
            return False
        if t==None and s!=None:
            return False
        if s.val==t.val:
            label1=self.isSubtree2(s.left,t.left,1)
            label2=self.isSubtree2(s.right,t.right,1)
            if label1 and label2:
                return True
        if mode==0:
            label1=self.isSubtree2(s.left,t,0)
            label2=self.isSubtree2(s.right,t,0)
            if label1 or label2:
                return True
        return False
        

Solution: https://leetcode.com/problems/subtree-of-another-tree/