# 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 isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool: if not p and not q: return True if not p or not q: return False if p.val != q.val: return False return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)