基数排序
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
public class RadixSort {
public static void main(String[] args) {
int[] arr = new int[8000000];
for (int i = 0; i < 8000000; i++) {
arr[i] = (int) (Math.random() * 8000000);
}
System.out.println("排序前");
Date data1 = new Date();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date1Str = simpleDateFormat.format(data1);
System.out.println("排序前的时间是=" + date1Str);
radixSort(arr);
Date data2 = new Date();
String date2Str = simpleDateFormat.format(data2);
System.out.println("排序前的时间是=" + date2Str);
}
public static void radixSort(int[] arr) {
int max = arr[0];
for(int i = 1; i < arr.length; i++) {
if (arr[i] > max) {
max = arr[i];
}
}
int maxLength = (max + "").length();
int[][] bucket = new int[10][arr.length];
int[] bucketElementCounts = new int[10];
for(int i = 0 , n = 1; i < maxLength; i++, n *= 10) {
for(int j = 0; j < arr.length; j++) {
int digitOfElement = arr[j] / n % 10;
bucket[digitOfElement][bucketElementCounts[digitOfElement]] = arr[j];
bucketElementCounts[digitOfElement]++;
}
int index = 0;
for(int k = 0; k < bucketElementCounts.length; k++) {
if(bucketElementCounts[k] != 0) {
for(int l = 0; l < bucketElementCounts[k]; l++) {
arr[index++] = bucket[k][l];
}
}
bucketElementCounts[k] = 0;
}
}
}
}