384. Shuffle an Array | LeetCode Solution

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.

Example 1:

Input
["Solution", "shuffle", "reset", "shuffle"]
[[[1, 2, 3]], [], [], []]
Output
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

Explanation
Solution solution = new Solution([1, 2, 3]);
solution.shuffle();    // Shuffle the array [1,2,3] and return its result.
                       // Any permutation of [1,2,3] must be equally likely to be returned.
                       // Example: return [3, 1, 2]
solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]
solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]

Constraints:

1 <= nums.length <= 50
-106 <= nums[i] <= 106
All the elements of nums are unique.
At most 104 calls in total will be made to reset and shuffle.

The solution to the above question is -

class Solution
{
public:
  vector<int> v;
  vector<int> org;
  Solution(vector<int> &nums)
  {
    v = nums;
    org = nums;
  }

  vector<int> reset()
  {
    v = org;
    return v;
  }

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

/**
 * 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();
 */