public int insert(T key)
{
//get ID
int id = unused.First.Value;
unused.RemoveFirst();
//Write into arrays
Positions[id - 1] = N;
HeapItem <T> newItem = new HeapItem <T>(id, key);
TheHeap[N] = newItem;
//Swap until invariant is fullfilled (going upwards in binary Tree)
int index = N + 1;
while (index / 2 > 0 && TheHeap[index / 2 - 1].key.CompareTo(key) > 0)
{
TheHeap[index - 1] = TheHeap[index / 2 - 1];
TheHeap[index / 2 - 1] = newItem;
Positions[TheHeap[index - 1].ID - 1] = index - 1;
Positions[newItem.ID - 1] = index / 2 - 1;
index = index / 2;
}
//increase length
++N;
return(id);
}
public void increaseKey(int ID, T key)
{
int index = Positions[ID - 1] + 1;
HeapItem <T> newItem = new HeapItem <T>(ID, key);
if (TheHeap[index - 1].key.CompareTo(key) < 0)
{
TheHeap[index - 1] = newItem;
int newIndex;
while (index * 2 < N + 1)
{
if (index * 2 == N)
{
if (TheHeap[index * 2 - 1].key.CompareTo(newItem.key) > 0)
{
break;
}
newIndex = index * 2;
}
else
{
if (TheHeap[index * 2 - 1].key.CompareTo(newItem.key) < 0 || TheHeap[index * 2].key.CompareTo(newItem.key) < 0)
{
if (TheHeap[index * 2 - 1].key.CompareTo(TheHeap[index * 2].key) < 0)
{
newIndex = index * 2;
}
else
{
newIndex = index * 2 + 1;
}
}
else
{
break;
}
}
TheHeap[index - 1] = TheHeap[newIndex - 1];
TheHeap[newIndex - 1] = newItem;
Positions[TheHeap[index - 1].ID - 1] = index - 1;
Positions[newItem.ID - 1] = newIndex - 1;
index = newIndex;
}
}
}
public void decreaseKey(int ID, T key)
{
int index = Positions[ID - 1] + 1;
HeapItem <T> newItem = new HeapItem <T>(ID, key);
if (TheHeap[index - 1].key.CompareTo(key) > 0)
{
TheHeap[index - 1] = newItem;
while (index / 2 > 0 && TheHeap[index / 2 - 1].key.CompareTo(key) > 0)
{
TheHeap[index - 1] = TheHeap[index / 2 - 1];
TheHeap[index / 2 - 1] = newItem;
Positions[TheHeap[index - 1].ID - 1] = index - 1;
Positions[newItem.ID - 1] = index / 2 - 1;
index = index / 2;
}
}
}
public T extractMinimum()
{
if (N == 0)
{
throw new NotSupportedException("Heap is empty.");
}
T key = TheHeap[0].key;
int id = TheHeap[0].ID;
//Replace first Item with last.
TheHeap[0] = TheHeap[N - 1];
TheHeap[N - 1] = null;
HeapItem <T> newItem = TheHeap[0];
//decrease N and add freed ID to unused list.
--N;
unused.AddFirst(id);
//Update Positions only when Heap not empty
if (N == 0)
{
return(key);
}
Positions[newItem.ID - 1] = 0;
//Swap until invariant is fullfilled (going downwards in binary Tree)
int index = 1;
int newIndex;
while (index * 2 < N + 1)
{
if (index * 2 == N)
{
if (TheHeap[index * 2 - 1].key.CompareTo(newItem.key) > 0)
{
break;
}
newIndex = index * 2;
}
else
{
if (TheHeap[index * 2 - 1].key.CompareTo(newItem.key) < 0 || TheHeap[index * 2].key.CompareTo(newItem.key) < 0)
{
if (TheHeap[index * 2 - 1].key.CompareTo(TheHeap[index * 2].key) < 0)
{
newIndex = index * 2;
}
else
{
newIndex = index * 2 + 1;
}
}
else
{
break;
}
}
TheHeap[index - 1] = TheHeap[newIndex - 1];
TheHeap[newIndex - 1] = newItem;
Positions[TheHeap[index - 1].ID - 1] = index - 1;
Positions[newItem.ID - 1] = newIndex - 1;
index = newIndex;
}
return(key);
}
