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// Recursive Solution
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// Time complexity : O(N*(2^N))
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// Space complexity : O(N*(2^N))
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class Solution {
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 public:
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  vector<vector<int>> ans;
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  void sub(vector<int> &nums, int i, vector<int> temp) {
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    if (i == nums.size()) {
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      ans.push_back(temp);
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      return;
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    }
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    sub(nums, i + 1, temp);
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    temp.push_back(nums[i]);
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    sub(nums, i + 1, temp);
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  }
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  vector<vector<int>> subsets(vector<int> &nums) {
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    vector<int> temp;
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    sub(nums, 0, temp); // or sub(nums, 0, vector<int> {});
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    return ans;
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  }
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};