Subtree of Another Tree

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. Tags: Tree

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# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def isSubtree(self, s: TreeNode, t: TreeNode) -> bool:
        if s == None or t == None:
            return False
        elif self.compare(s, t):
            return True
        else:
            return self.isSubtree(s.left, t) or self.isSubtree(s.right, t)
    
    def compare(self, s, t):
        if s == None and t == None:
            return True
        elif s == None or t == None:
            return False
        elif s.val == t.val:
            return self.compare(s.left, t.left) and self.compare(s.right, t.right)
        else:
            return False