384. Shuffle an Array

import java.util.Random; 

class Solution {
    int[] original;
    int[] copy;
    Random rand; 
    public Solution(int[] nums) {
        original = new int[nums.length];
        copy = new int[nums.length];
        rand = new Random();
        for(int i=0;i<nums.length;i++){
            original[i] = nums[i];
            copy[i] = nums[i];
        }
    }
    
    /** Resets the array to its original configuration and return it. */
    public int[] reset() {
        return original;
    }
    
    /** Returns a random shuffling of the array. */
    public int[] shuffle() {
        int len = original.length-1;
        while(len>=0){
            int index = rand.nextInt(original.length);
            int temp = copy[index];
            copy[index] = copy[len];
            copy[len] = temp;
            len--;
        }
        return copy;
    }
}

/**
 * Your Solution object will be instantiated and called as such:
 * Solution obj = new Solution(nums);
 * int[] param_1 = obj.reset();
 * int[] param_2 = obj.shuffle();
 */