Java Solution || 3ms faster && 94.41% faster || easy to understand
\nclass Solution {\n    public List<Integer> intersection(int[][] arr) {\n        List<Integer> list = new ArrayList<>();\n        for (int i : arr[0]) {\n     
```\nclass Solution {\n    public List<Integer> intersection(int[][] arr) {\n        List<Integer> list = new ArrayList<>();\n        for (int i : arr[0]) {\n            if (helper(i, arr, 1)) list.add(i);\n        }\n        Collections.sort(list);\n        return list;\n    }\n\n    private static boolean helper(int target, int[][] arr, int start) {\n        for (int i = start; i < arr.length; i++) {\n            boolean b = false;\n            for (int k : arr[i]){\n                if (k == target) {\n                    b = true;\n                    break;\n                }\n            }\n            if (!b) return false;\n        }\n        return true;\n    }\n}\n```
['Array', 'Java']