java快速排序

O(nlog(n)时间和O(logn)的栈空间

package contcurrentandalgorithm;

/**

 *

 * @author Administrator

 * zyyjiao@mail.ustc.edu.cn
 */

public class QSort {

    public static void main(String[] args) {

        int a[] = {3, 4, 2, 1, 6, 5, 7, 8};

        qSort(a, 0, 7);

        for (int i = 0; i < a.length; i++) {

            System.out.println(a[i]);

        }

    }

    public static void qSort(int a[], int left, int right) {

        int i = left;

        int j = right;

        int temp = a[i];

        if (left >= right) {

            return;

        }

        while (i < j) {

            while (i < j && temp < a[j]) {

                j--;

            }

            a[i] = a[j];

            while (i < j && temp > a[i]) {

                i++;

            }

            a[j] = a[i];

        }

        a[i] = temp;

        qSort(a, left, j - 1);

        qSort(a, j + 1, right);

    }

}