堆的基本操作

void shiftdown(int i, int n)
{
	int k, t;
	t=heap[i]; k=2*i;
	while(k<=n)
	{
		if((k<n)&&(heap[k]>heap[k+1]))k++;
		if(t>heap[k]){heap[i]=heap[k];i=k;k=2*i;}
		else break;
	}
	heap[i]=t;
}
void del()
{
	heap[1]=heap[n--];
	if(n>0)	shiftdown(1, n);
}
void shiftup(int x)
{
	int t=heap[x], k=x/2;
	while(k)
	{
		if(t<heap[k]){heap[x]=heap[k]; x=k; k=k/2;}
		else break;
	}
	heap[x]=t;
}
void insert(int x)
{
	heap[++n]=x;
	shiftup(n);
}