[JAVA] [100% faster] [List] [O(n) Single Pass]
```\nclass Solution {\n    public int calPoints(String[] ops) {\n       LinkedList list = new LinkedList<>();\n        int sum = 0;\n        for(var op : ops){\
```\nclass Solution {\n    public int calPoints(String[] ops) {\n       LinkedList<Integer> list = new LinkedList<>();\n        int sum = 0;\n        for(var op : ops){\n            switch (op){\n                case "C":{\n                    sum -= list.removeLast();\n                    //list.removeLast();\n                    break;\n                }\n                case "D":{\n                    int item = list.getLast();\n                    list.addLast(item*2);\n                    sum+=item*2;\n                    break;\n                }\n                case "+":{\n                    int value = list.get(list.size()-2)+list.getLast();\n                    list.addLast(value);\n                    sum+=value;\n                    break;\n                }\n                default:{\n                    list.addLast(Integer.parseInt(op));\n                    sum+=Integer.parseInt(op);\n                    break;\n                }\n            }\n        }\n        return sum;\n    }\n}
['Java']