384. Shuffle an Array

#### QUESTION:

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();
``````

#### SOLUTION:

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

/** Resets the array to its original configuration and return it. */
public int[] reset() {
return instance;
}

/** Returns a random shuffling of the array. */
public int[] shuffle() {
ArrayList<Integer> list = new ArrayList<>();
for(int i = 0;i<instance.length;i++) list.add(instance[i]);
int[] result = new int[instance.length];
for(int i = 0;i<result.length;i++){
result[i] = list.remove(random.nextInt(instance.length-i));
}
return result;
}
}
``````
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