排序算法（七）

public class QuickSort {

    public static void main(String[] args) {
        int[] a = { 12, 23, 34, 45, 54, 43, 32, 21 };
        quickSort(a, 0, a.length - 1);

        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
    }

    public static void quickSort(int[] a, int low, int high) {
        if (low < high) {
            int privotLoc = partition(a, low, high);// 将表一分为二
            quickSort(a, low, privotLoc - 1);// 递归对低子表递归排序
            quickSort(a, privotLoc + 1, high);// 递归对高子表递归排序
        }
    }

    public static int partition(int[] a, int low, int high) {
        int privotkey = a[low]; // 基准元素
        while (low < high) { // 从表的俩端，交替的向中间扫描
            while (low < high && a[high] >= privotkey) { // 从high
                                                            // 所指位置向前搜索，至多到low+1
                                                            // 位置。将比基准元素小的交换到低端
                --high;
            }
            swap(a, low, high);
            while (low < high && a[low] <= privotkey) {
                ++low;
            }
            swap(a, low, high);
        }
        return low;
    }

    public static void swap(int a[], int low, int high) {
        int temp = a[low];
        a[low] = a[high];
        a[high] = temp;
    }
}