Clear Python 3 solution faster than 95% without using stack; comments provided
\nclass Solution:\n    def isValidSerialization(self, preorder: str) -> bool:\n        nodes = deque(preorder.split(\',\'))\n        count = 1    # number(s) of
```\nclass Solution:\n    def isValidSerialization(self, preorder: str) -> bool:\n        nodes = deque(preorder.split(\',\'))\n        count = 1    # number(s) of \'null\'/\'None\' to take care of at any point in time \n        while nodes:\n            node = nodes.popleft()\n            if node != \'#\':\n                count += 1 \n            else:\n                count -= 1    # one less \'null\'/\'None\' to take care of\n            if not count and nodes:    # if there are still nodes left\n                return False\n        if count:    # if the number of \'null\'/\'None\' in the input string is less than what is needed \n            return False\n        return True\n```
['Python', 'Python3']