problem384

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384. Shuffle an Array (Medium)

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.

Hints

Hint 1

The solution expects that we always use the original array to shuffle() else some of the test cases fail. (Credits; @snehasingh31)