使用二维数组递归对Java进行基数排序

import java.util.Arrays;

public class RadixSort {
    public static void radixSort(int[] arr) {
        if (arr == null || arr.length == 0) {
            return;
        }
        
        int max = getMax(arr);
        int maxDigit = getDigit(max);
        
        int[][] bucket = new int[10][arr.length];
        int[] count = new int[10];
        
        for (int digit = 1; digit <= maxDigit; digit++) {
            for (int num : arr) {
                int index = getDigit(num, digit);
                bucket[index][count[index]++] = num;
            }
            
            int k = 0;
            for (int i = 0; i < bucket.length; i++) {
                if (count[i] != 0) {
                    for (int j = 0; j < count[i]; j++) {
                        arr[k++] = bucket[i][j];
                    }
                    count[i] = 0;
                }
            }
        }
    }
    
    private static int getMax(int[] arr) {
        int max = arr[0];
        for (int num : arr) {
            if (num > max) {
                max = num;
            }
        }
        return max;
    }
    
    private static int getDigit(int num) {
        if (num == 0) {
            return 1;
        }
        
        int digit = 0;
        while (num != 0) {
            num /= 10;
            digit++;
        }
        return digit;
    }
    
    private static int getDigit(int num, int digit) {
        return (num / (int) Math.pow(10, digit - 1)) % 10;
    }
    
    public static void main(String[] args) {
        int[] arr = {53, 3, 542, 748, 14, 214, 154, 63, 616};
        radixSort(arr);
        System.out.println(Arrays.toString(arr));
    }
}