Simple solution - 2ms (with comments !!)
\nclass Solution {\n    public List<Integer> intersection(int[][] nums) {\n        List<Integer> res = new ArrayList<>();\n        int count[] = new int[1001]; 
```\nclass Solution {\n    public List<Integer> intersection(int[][] nums) {\n        List<Integer> res = new ArrayList<>();\n        int count[] = new int[1001]; // stores the number of array which has that element i\n        for(int numsArray[]: nums)\n            for(int num: numsArray)\n                count[num]++;\n        \n        int n = nums.length;\n        for(int i=0;i<1001;i++)\n            if(count[i]==n) // if the count is == size of the array, then it is present in every array\n                res.add(i);\n        return res;\n    }\n}\n```
['Java']