Shuffle an Array.cpp

/*
Shuffle an Array
===============

Given an integer array nums, design an algorithm to randomly shuffle the array.

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 <= 200
-106 <= nums[i] <= 106
All the elements of nums are unique.
At most 5 * 104 calls will be made to reset and shuffle.
*/

class Solution
{
  vector<int> safeArray;

public:
  Solution(vector<int> &nums)
  {
    safeArray = nums;
  }

  /** Resets the array to its original configuration and return it. */
  vector<int> reset()
  {
    return safeArray;
  }

  /** Returns a random shuffling of the array. */
  vector<int> shuffle()
  {
    vector<int> myArray = safeArray;
    if (myArray.size() == 0)
      return myArray;

    for (int j = 1; j < myArray.size(); ++j)
    {
      int i = rand() % (j + 1);
      swap(myArray[i], myArray[j]);
    }
    return myArray;
  }
};

/**
 * 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();
 */