384. Shuffle an Array

Shuffle a set of numbers without duplicates.

Example:

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       // 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();
      
      
      
      

       
       
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       class Solution {
       
       
    private int[] original;
       
       
    private Random rng = new Random();
       
       
    private int[] copy;
       
       
    private int num;
       
       
    public Solution(int[] nums) {
       
       
        original = nums;
       
       
        copy=original.clone();
       
       
        num=original.length;
       
       
    }
       
       

       
       
    /** 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 n = num;
       
       
        while(n>1) {
       
       
            n--;
       
       
            int k = rng.nextInt(n + 1);
       
       
            int value = copy[k];
       
       
            copy[k] = copy[n];
       
       
            copy[n] = value;
       
       
        }
       
       
        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();
       
       
 */
      
      
      
      

       
       
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