排序--快速排序

    public static int getKey(int[] arr, int low, int high)
    {
        int key = low;
        while(low < high)
        {
            while(low < high && arr[high] > arr[key])
            {
                high--;
            }
            int t = arr[high];
            arr[high] = arr[key];
            arr[key] = t;
            key = high;
            while(low < high && arr[low] < arr[key])
            {
                low++;
            }
            int t2 = arr[low];
            arr[low] = arr[key];
            arr[key] = t2;
            key = low;
        }
        return key;
    }

    public static void QuickSort(int[] arr, int low, int high)
    {
        if(low < high)
        {
            int key = getKey(arr, low, high);
            QuickSort(arr, low, key - 1);
            QuickSort(arr, key + 1, high);
        }
    }