一亿条排序,执行时间为13.664s
缺点,如果排序之前是有序的,会很慢。
相当于T(n) = T(n-1) + n;复杂度为o(n*n)
package test2018.test08;
import java.util.Arrays;
import java.util.Random;
/**
* Filename: Class8.java Description: Company: sendinfo.com.cn Inc.
* 快速排序:在排序时候,找一个数,把比这个数大的放在一侧,小的放在另一侧
*
* @author: guzhangyan
* @date: 2018年8月8日 上午11:16:57
*/
public class Class8Kuaisupaixu {
public static void main(String[] args) {
int[] shuZu = new int[100000000];
Random random = new Random();
for (int i = 0; i < shuZu.length; i++) {
shuZu[i] = random.nextInt(1000000);
}
// System.out.println(Arrays.toString(shuZu));
long stratTime = System.currentTimeMillis();
kuaisupaixu(shuZu);
// Arrays.sort(shuZu);
/*
* for (int i = 1; i < shuZu.length; i++) { if (shuZu[i] - shuZu[i - 1] < 0) {
* System.out.println(i); } }
*/
// System.out.println(Arrays.toString(shuZu));
long endTime = System.currentTimeMillis();
System.out.println("快速排序时间:" + (endTime - stratTime));
}
private static void kuaisupaixu(int[] shuZu) {
kuaisupaixu(shuZu, 0, shuZu.length - 1);
}
private static void kuaisupaixu(int[] shuZu, int start, int end) {
if (start >= end) {
return;
}
int startNum = shuZu[start];
int i, j = 0;
int temp = 0;
// 将比shuzu[start]的数字后移,得到中间值,然后用这个值和shuzu[start]进行比较(如果大了,就把start位和i位交换否则和i-1位交换)
for (i = start + 1, j = end; i < j;) {
if (shuZu[i] <= startNum) {
i++;
} else {
temp = shuZu[i];
shuZu[i] = shuZu[j];
shuZu[j] = temp;
j--;
}
}
if (shuZu[i] > startNum) {
i--;
}
temp = shuZu[i];
shuZu[i] = shuZu[start];
shuZu[start] = temp;
kuaisupaixu(shuZu, start, i - 1);
kuaisupaixu(shuZu, i + 1, end);
}
}