基数排序（桶排序）

package A;

import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;

public class JosePhu {
    public static void main(String[] args) {
        Method method=new Method();
        //int[] a={53,3,542,748,14,214};
        int[] a={123,9,0,0,123,345345353,35,4,6,76,87,4,3};
        method.radixSort(a);
        System.out.println(Arrays.toString(a));
    }
}

package A;

import java.util.Arrays;

public class Method {
    public void radixSort(int[] a){//速度很快，比前面的快排什么的都要快，但是是以内存换时间，能测试的数据具体看电脑配置
        int max=a[0];
        for (int i = 0; i < a.length; i++) {
            if (a[i]>max){
                max=a[i];
            }
        }//for find the maximum
        int maxlength=(max+"").length();//为了使max变成一个字符串

        int[][] bucket=new int[10][a.length];
        int[] count=new int[10];

        for (int i = 0,n=1; i < maxlength; i++,n*=10) {
            for (int j = 0; j < a.length; j++) {//pick up
                int temp=a[j]/n%10;
                bucket[temp][count[temp]]=a[j];
                count[temp]++;//the record is for easy access
            }
            int index=0;
            for (int k = 0; k < count.length; k++) {//put in
                if (count[k]!=0){
                    for (int l = 0; l < count[k]; l++) {
                        a[index]=bucket[k][l];
                        index++;
                    }
                }
                count[k]=0;
            }
        }
        /*//one
        for (int j = 0; j < a.length; j++) {//pick up
            int temp=a[j]%10;
            bucket[temp][count[temp]]=a[j];
            count[temp]++;//the record is for easy access
        }
        int index=0;
        for (int k = 0; k < count.length; k++) {//put in
            if (count[k]!=0){
                for (int l = 0; l < count[k]; l++) {
                    a[index]=bucket[k][l];
                    index++;
                }
            }
            count[k]=0;//count是记录的，所以要置零。bucket一直被赋值，每赋一个值，它原先的就被替换了，所以不用置零
        }
        System.out.println("第一轮，对个位数排序处理a="+ Arrays.toString(a));

        //two
        for (int j = 0; j < a.length; j++) {
            int temp=a[j]/10%10;
            bucket[temp][count[temp]]=a[j];
            count[temp]++;
        }
        index=0;
        for (int k = 0; k < count.length; k++) {
            if (count[k]!=0){
                for (int l = 0; l < count[k]; l++) {
                    a[index]=bucket[k][l];
                    index++;
                }
            }
            count[k]=0;
        }
        System.out.println("第二轮，对个位数排序处理a="+ Arrays.toString(a));

        for (int j = 0; j < a.length; j++) {
            int digiOfElement=a[j]/100%10;
            bucket[digiOfElement][count[digiOfElement]]=a[j];
            count[digiOfElement]++;
        }
        index=0;
        for (int k = 0; k < count.length; k++) {
            if (count[k]!=0){
                for (int l = 0; l < count[k]; l++) {
                    a[index]=bucket[k][l];
                    index++;
                }
            }
            count[k]=0;
        }
        System.out.println("第san轮，对个位数排序处理a="+ Arrays.toString(a));*/
    }
}