## Algorithm

Problem Name: 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.

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`.

## Code Examples

### #1 Code Example with Java Programming

```Code - Java Programming```

``````
class Solution {

private int[] nums;
private Random random;

public Solution(int[] nums) {
this.nums = nums;
random = new Random();
}

public int[] reset() {
return nums;
}

public int[] shuffle() {
if (nums == null) return null;
int[] shuf = nums.clone();
for (int i=1;i < shuf.length;i++) {
int l = random.nextInt(i+1);
swap(shuf, i, l);
}

return shuf;
}

private void swap(int[] arr, int a, int b) {
int temp = arr[a];
arr[a] = arr[b];
arr[b] = temp;
}
}
``````
Copy The Code &

Input

cmd
["Solution", "shuffle", "reset", "shuffle"] [[[1, 2, 3]], [], [], []]

Output

cmd
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

### #2 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const Solution = function(nums) {
this.original = nums;
};

Solution.prototype.reset = function() {
return this.original;
};

Solution.prototype.shuffle = function() {
const res = [];
const len = this.original.length;
let idx = 0;
let i = 0;
while (idx  < = len - 1) {
i = Math.floor(Math.random() * len);
if (res[i] == null) {
res[i] = this.original[idx];
idx += 1;
}
}
return res;
};
``````
Copy The Code &

Input

cmd
["Solution", "shuffle", "reset", "shuffle"] [[[1, 2, 3]], [], [], []]

Output

cmd
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

### #3 Code Example with Python Programming

```Code - Python Programming```

``````
class Solution:

def __init__(self, nums: List[int]):
self.arr = nums
self.org = nums[:]

def reset(self) -> List[int]:
"""
Resets the array to its original configuration and return it.
"""
self.arr = self.org[:]
return self.arr

def shuffle(self) -> List[int]:
"""
Returns a random shuffling of the array.
"""
random.shuffle(self.arr)
return self.arr

# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()
``````
Copy The Code &

Input

cmd
["Solution", "shuffle", "reset", "shuffle"] [[[1, 2, 3]], [], [], []]

Output

cmd
[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]