private static void radixSort(int[] a) {

        int maxOne = a[0], exp = 1, size = a.length;

        for (int anA : a) if (anA > maxOne) maxOne = anA;//Get max

        while (maxOne / exp > 0) {

            int[] bucket = new int[10];

            for (int num : a) {//get count of each digit
                int digit = (num / exp) % 10;
                bucket[digit] += 1;
            }

            for (int i = 1; i <= 9; i++)//define range of
                bucket[i] += bucket[i - 1];//numbers with the same digit

            int temp[] = new int[size];

            for (int i = size - 1; i >= 0; i--) {
                int digit = (a[i] / exp) % 10;
                temp[--bucket[digit]] = a[i];//copy elements to
            }                                //temp array

            for (int i = 0; i < size; i++) a[i] = temp[i];//copy temp to input array

            exp *= 10;//go next digit

        }

    }