public int[] shuffle() {
        for(int i=0; i<a.length; i++){
            int rand=(int) (Math.random()* (a.length));
            int temp=a[i];
            a[i]=a[rand];
            a[rand]=temp;
        }
        return a;
    }
Returns a random shuffling of the array.
src/problems/medium/ShuffleanArray.java