public void DecreaseKey(int index, T item)
{
int p = qp[index];
if (SortUtil.IsGreaterThan(keys[index], item))
{
keys[index] = item;
Swim(p);
}
}
public int DelMin()
{
var item = pq[1];
SortUtil.Exchange(pq, 1, N);
qp[pq[1]] = 1;
qp[pq[N]] = N;
N--;
Sink(1);
return(item);
}
private void Swim(int k)
{
while (k > 1)
{
var parent = k / 2;
if (SortUtil.IsLessThan(keys[pq[k]], keys[pq[parent]]))
{
SortUtil.Exchange(pq, k, parent);
qp[pq[k]] = k;
qp[pq[parent]] = parent;
k = parent;
}
else
{
break;
}
}
}
public void Enqueue(int index, T item)
{
var p = qp[index];
if (p == -1)
{
Insert(index, item);
}
else
{
if (SortUtil.IsLessThan(keys[index], item))
{
keys[index] = item;
Sink(p);
}
else
{
keys[index] = item;
Swim(p);
}
}
}
private void Sink(int k)
{
while (k * 2 <= N)
{
int child = 2 * k;
if (child < N && SortUtil.IsLessThan(keys[pq[child + 1]], keys[pq[child]]))
{
child++;
}
if (SortUtil.IsLessThan(keys[pq[child]], keys[pq[k]]))
{
SortUtil.Exchange(pq, child, k);
qp[pq[child]] = child;
qp[pq[k]] = k;
k = child;
}
else
{
break;
}
}
}
