# LeetCode 384. Shuffle an Array

## Description

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();```

## Explanation

Randomly sets original elements new positions.

## Python Solution

``````class Solution:

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

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

def shuffle(self) -> List[int]:
"""
Returns a random shuffling of the array.
"""
shuffle_nums = [0 for i in range(0, len(self.original_nums))]

new_positions = set()

for i in range(0, len(self.original_nums)):
num = self.original_nums[i]

new_position = randint(0, len(self.original_nums) - 1)
while new_position in new_positions:
new_position = randint(0, len(self.original_nums) - 1)

shuffle_nums[new_position] = num

return shuffle_nums

# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()``````
• Time complexity: O(n).
• Space complexity: O(n).

## 2 Thoughts to “LeetCode 384. Shuffle an Array”

1. Jack says:

Hi,