384. Shuffle an Array.cpp

/*
Link: https://leetcode.com/problems/shuffle-an-array/

Shuffle a set of numbers without duplicates.

Example:

// Init an array with set 1, 2, and 3.
int[] nums = {1,2,3};
Solution solution = new Solution(nums);

// Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must equally likely to be returned.
solution.shuffle();

// Resets the array back to its original configuration [1,2,3].
solution.reset();

// Returns the random shuffling of array [1,2,3].
solution.shuffle();
*/

class Solution {
public:
    vector<int> array;
    vector<int> original;
    Solution(vector<int>& nums) {
        array = nums;
        original = nums;
    }
    
    /** Resets the array to its original configuration and return it. */
    vector<int> reset() {
        return original;
    }
    
    /** Returns a random shuffling of the array. */
    vector<int> shuffle() {
        int n = array.size();
        for (int i = 0; i < n; i++) {
            swap(array[i], array[(rand() + i) % n]);
        }
        
        return array;
    }
};

/**
 * 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();
 */