384. Shuffle an Array

Given an integer array nums, design an algorithm to randomly shuffle the array. All permutations of the array should be equally likely as a result of the shuffling.

Implement the Solution class:

• Solution(int[] nums) Initializes the object with the integer array nums.
• int[] reset() Resets the array to its original configuration and returns it.
• int[] shuffle() Returns a random shuffling of the array.

Fisher–Yates shuffle

class Solution {
    vector<int> _origin;
    vector<int> _shuffle;
public:
    Solution(vector<int>& nums) {
        _origin = vector<int>(nums.begin(), nums.end());
        _shuffle = vector<int>(_origin.begin(), _origin.end());
    }

    vector<int> reset() {
        _shuffle = vector<int>(_origin.begin(), _origin.end());
        return _shuffle;
    }

    vector<int> shuffle() {
        for(int i = 0; i < _shuffle.size(); i++) {
            swap(_shuffle[rand() % _shuffle.size()], _shuffle[i]);
        }
        return _shuffle;
    }
};

/**
 * Your Solution object will be instantiated and called as such:
 * Solution* obj = new Solution(nums);
 * vector<int> param_1 = obj->reset();
 * vector<int> param_2 = obj->shuffle();
 */