class Solution {private:    vector<int> arr, idx;public:    Solution(vector<int> nums) {        srand(time(NULL));        idx.resize(nums.size());        arr.resize(nums.size());        for(int i = 0; i < nums.size(); ++i)        {            arr[i] = nums[i];            idx[i] = nums[i];        }    }        /** Resets the array to its original configuration and return it. */    vector<int> reset() {        for(int i = 0; i < arr.size(); ++i)        {            arr[i] = idx[i];        }        return arr;    }        /** Returns a random shuffling of the array. */    vector<int> shuffle() {        for(int i = arr.size() - 1; i >= 0; --i)        {            int j = rand() % (i + 1);            swap(arr[i], arr[j]);        }                return arr;    }};