排序之-------堆排

void adjustdown(int a[], int root, int size)

{

        int left = root * 2 + 1;

        int right = left + 1;

        int key = left;

        while (left<size)

        {

               if (right<size&&a[left]<a[right])

               {

                       key = right;

               }

               if (a[key]>a[root])

               {

                       swap(a[root], a[key]);

                       root = key;

                       left = root * 2 + 1;

                       right = left + 1;

                       key = left;

               }

               else

               {

                       break;

               }

        }

}

void Heapsort(int a[], int size)

{

        int begin = size / 2 - 1;

        for (; begin>=0; begin--)

        {

               adjustdown(a, begin, size);

        }

        int end = size - 1;

        while (end)

        {

               swap(a[0], a[end]);

               adjustdown(a, 0, end);

               end--;

        }

}