快速排序

    /**
     * 交换排序-2.快速排序
     * 
     * @param array
     *            数组
     * @param start
     *            开始序号
     * @param end
     *            结束序号
     */
    public static void quickSort(int[] array, int start, int end) {
        if (start < end) {
            int key = array[start];
            int i = start;

            for (int j = start + 1; j <= end; j++) {
                if (array[j] < key) {
                    if (i + 1 != j) {
                        // 将array[j] 与 array[i + 1]交换
                        array[j] = array[j] ^ array[i + 1];
                        array[i + 1] = array[i + 1] ^ array[j];
                        array[j] = array[j] ^ array[i + 1];
                    }
                    i++;
                }
            }

            array[start] = array[i];
            array[i] = key;
            System.out.println("键Key:" + key + ",结果:" + Arrays.toString(array));
            quickSort(array, start, i - 1);
            quickSort(array, i + 1, end);
        }
    }

    @Test
    public void testQuickSort2() {
        int[] array = { 1, 8, 3, 5, 4, 6, 2, 7, 9 };
        int[] expectResult = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
        Sort.quickSort(array, 0, 8);
        Assert.assertArrayEquals(expectResult, array);
    }

键Key:1,结果:[1, 8, 3, 5, 4, 6, 2, 7, 9]
键Key:8,结果:[1, 7, 3, 5, 4, 6, 2, 8, 9]
键Key:7,结果:[1, 2, 3, 5, 4, 6, 7, 8, 9]
键Key:2,结果:[1, 2, 3, 5, 4, 6, 7, 8, 9]
键Key:3,结果:[1, 2, 3, 5, 4, 6, 7, 8, 9]
键Key:5,结果:[1, 2, 3, 4, 5, 6, 7, 8, 9]