100.相同的树

# 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 isSameTree0(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if p is None  and q is None:
            return True
        if p is None or q is None:
            return False 
        if p.val !=q.val:
            return False
        return self.isSameTree(p.left,q.left) and self.isSameTree(p.right,q.right)
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if p is None  and q is None:
            return True
        if p is None or q is None:
            return False
        if p.val !=q.val:
            return False
        # stack 
        s1=[]
        s2=[]
        s1.append(p)
        s2.append(q)
        while s1 and s2 :
            temp1 = s1.pop()
            temp2 =s2.pop()
            if temp1 is None  and temp2 is None:
                continue
            if temp1 is None or temp2 is None:
                return False
            if temp1.val !=temp2.val:
                return False
            
            s1.append(temp1.right)
          
            s1.append(temp1.left)
            
            s2.append(temp2.right)
            
            s2.append(temp2.left)
        return not s1 and not s2