101. Symmetric Tree - LeetCode Solution

# 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 isSymmetric(self, root: Optional[TreeNode]) -> bool:
        q = [root, None]
        s = []
        count = 0
        
        while len(q) != 0:
            k = q.pop(0)
            
            if k == None:
                count +=1
                if s != s[::-1]:
                    return False

                s = []
                q.append(None)
                if count >1:
                    break
                continue
            count = 0
            if k == 101:
                s.append(101)
                continue
            if k.right:
                q.append(k.right)
            else:
                q.append(101)
            if k.left:
                q.append(k.left)
            else:
                q.append(101)
            
            s.append(k.val)
        return True