Simple java solution
Complexity\n- Time complexity: O(n) where n is the size of the array\n\n- Space complexity: O(n) where n is the size of the array\n\n# Code\n\nclass Solution {\
# Complexity\n- Time complexity: $$O(n)$$ where n is the size of the array\n\n- Space complexity: $$O(n)$$ where n is the size of the array\n\n# Code\n```\nclass Solution {\n    public int minImpossibleOR(int[] nums) {\n        Map<Integer,Integer> nm=new HashMap<>();\n        for(int i:nums)\n        {\n            nm.put(i, nm.getOrDefault(i,0)+1);\n        }\n        int x=1;\n        while(nm.containsKey(x))\n        {\n            x*=2;\n        }\n        return x;\n    }\n}\n```
['Hash Table', 'Java']