十大排序算法之基数排序
取得数组中的最大数，并取得位数；
arr为原始数组，从最低位开始取每个位组成radix数组；
对radix进行计数排序（利用计数排序适用于小范围数的特点）；
这里给出一份Java的代码实现：
public class BucketSorted {public void bucketSort(int[] a) {if (a.length == 0) {return ;}int i, sortedIndex = 0;int minValue = Integer.MAX_VALUE;int maxValue = Integer.MIN_VALUE;for (i = 0; i < a.length; i++) {minValue = Math.min(minValue, a[i]);maxValue = Math.max(maxValue, a[i]);}int bucketCount = (maxValue - minValue) / a.length + 1;ArrayList<ArrayList<Integer>> buckets = new ArrayList<>(bucketCount);for (i = 0; i < bucketCount; i++) {buckets.add(new ArrayList<>());}for (i = 0; i < a.length; i++) {buckets.get((a[i] - minValue) / a.length).add(a[i]);}for (i = 0; i < bucketCount; i++) {ArrayList<Integer> bucket = buckets.get(i);Collections.sort(bucket);for (i = 0; i < bucket.size(); i++) {a[sortedIndex ++] = bucket.get(i);}}}}