BEATS 88% || SIMPLY JAVA || WITH COMMENTS
\n\n# Complexity\n- Time complexity:\nO(n)\n\n- Space complexity:\nO(1)\n\n# Code\n\nclass Solution {\n    public boolean isValidSerialization(String preorder) 
\n\n# Complexity\n- Time complexity:\nO(n)\n\n- Space complexity:\nO(1)\n\n# Code\n```\nclass Solution {\n    public boolean isValidSerialization(String preorder) {\n        String[]arr=preorder.split(",");\n        int slots=1;//only for root node in the beginning\n\n        for(String node:arr){\n            slots--;//used up one slot\n            if(slots<0)return false;\n            //at any moment if slots become negative that means we dont have slots left but we\'re trying to insert more nodes so return false there\n            if(!node.equals("#")){\n                slots+=2;//if the current node is not null then it gives rise to 2 new children so 2 slots opens up\n            }\n        }\n        return slots==0;//lastly if slots become 0 then we have successfully used all slots in the tree\n    }\n}\n```
['Java']