void bubbleUpMax(int i)
{
if (i > 0)
{
T max = heap[i].last, iv = max;
PriorityQueueHandle maxhandle = heap[i].lasthandle;
int p = (i + 1) / 2 - 1;
while (i > 0)
{
if (comparer.Compare(iv, max = heap[p = (i + 1) / 2 - 1].last) > 0)
{
updateLast(i, max, heap[p].lasthandle);
max = iv;
i = p;
}
else
{
break;
}
}
updateLast(i, iv, maxhandle);
}
}
/// <summary>
/// Replace an item with a handle in a priority queue with a new item.
/// Typically used for changing the priority of some queued object.
/// </summary>
/// <param name="handle">The handle for the old item</param>
/// <param name="item">The new item</param>
/// <returns>The old item</returns>
public T Replace(PriorityQueueHandle handle, T item)
{
int cell;
bool isfirst;
checkHandle(handle, out cell, out isfirst);
if (size == 0)
{
throw new InvalidOperationException("Heap is empty");
}
T retval;
if (isfirst)
{
retval = heap[cell].first;
heap[cell].first = item;
if (size == 1)
{
}
else if (size == 2 * cell + 1) // cell == lastcell
{
int p = (cell + 1) / 2 - 1;
if (comparer.Compare(item, heap[p].last) > 0)
{
PriorityQueueHandle thehandle = heap[cell].firsthandle;
updateFirst(cell, heap[p].last, heap[p].lasthandle);
updateLast(p, item, thehandle);
bubbleUpMax(p);
}
else
{
bubbleUpMin(cell);
}
}
else if (heapifyMin(cell))
{
bubbleUpMax(cell);
}
else
{
bubbleUpMin(cell);
}
}
else
{
retval = heap[cell].last;
heap[cell].last = item;
if (heapifyMax(cell))
{
bubbleUpMin(cell);
}
else
{
bubbleUpMax(cell);
}
}
return(retval);
}
/// <summary>
/// Check safely if a handle is valid for this queue and if so, report the corresponding queue item.
/// </summary>
/// <param name="handle">The handle to check</param>
/// <param name="item">If the handle is valid this will contain the corresponding item on output.</param>
/// <returns>True if the handle is valid.</returns>
public bool Find(PriorityQueueHandle handle, out T item)
{
PriorityQueueHandle myhandle = handle;
if (myhandle == null)
{
item = default(T);
return(false);
}
int toremove = myhandle.index;
int cell = toremove / 2;
bool isfirst = toremove % 2 == 0;
{
if (toremove == -1 || toremove >= size)
{
item = default(T);
return(false);
}
PriorityQueueHandle actualhandle = isfirst ? heap[cell].firsthandle : heap[cell].lasthandle;
if (actualhandle != myhandle)
{
item = default(T);
return(false);
}
}
item = isfirst ? heap[cell].first : heap[cell].last;
return(true);
}
void bubbleUpMin(int i)
{
if (i > 0)
{
T min = heap[i].first, iv = min;
PriorityQueueHandle minhandle = heap[i].firsthandle;
int p = (i + 1) / 2 - 1;
while (i > 0)
{
if (comparer.Compare(iv, min = heap[p = (i + 1) / 2 - 1].first) < 0)
{
updateFirst(i, min, heap[p].firsthandle);
min = iv;
i = p;
}
else
{
break;
}
}
updateFirst(i, iv, minhandle);
}
}
private bool add(PriorityQueueHandle itemhandle, T item)
{
if (size == 0)
{
size = 1;
updateFirst(0, item, itemhandle);
return(true);
}
if (size == 2 * heap.Length)
{
Interval[] newheap = new Interval[2 * heap.Length];
Array.Copy(heap, newheap, heap.Length);
heap = newheap;
}
if (size % 2 == 0)
{
int i = size / 2, p = (i + 1) / 2 - 1;
T tmp = heap[p].last;
if (comparer.Compare(item, tmp) > 0)
{
updateFirst(i, tmp, heap[p].lasthandle);
updateLast(p, item, itemhandle);
bubbleUpMax(p);
}
else
{
updateFirst(i, item, itemhandle);
if (comparer.Compare(item, heap[p].first) < 0)
{
bubbleUpMin(i);
}
}
}
else
{
int i = size / 2;
T other = heap[i].first;
if (comparer.Compare(item, other) < 0)
{
updateLast(i, other, heap[i].firsthandle);
updateFirst(i, item, itemhandle);
bubbleUpMin(i);
}
else
{
updateLast(i, item, itemhandle);
bubbleUpMax(i);
}
}
size++;
return(true);
}
/// <summary>
/// Find the current least item of this priority queue.
/// </summary>
/// <param name="handle">On return: the handle of the item.</param>
/// <returns>The least item.</returns>
public T FindMin(out PriorityQueueHandle handle)
{
if (size == 0)
{
throw new InvalidOperationException("Heap is empty");
}
handle = heap[0].firsthandle;
return(heap[0].first);
}
private void updateFirst(int cell, T item, PriorityQueueHandle handle)
{
heap[cell].first = item;
if (handle != null)
{
handle.index = 2 * cell;
}
heap[cell].firsthandle = handle;
}
/// <summary>
/// Remove the largest item from this priority queue.
/// </summary>
/// <param name="handle">On return: the handle of the removed item.</param>
/// <returns>The removed item.</returns>
public T DeleteMax(out PriorityQueueHandle handle)
{
if (size == 0)
{
throw new InvalidOperationException("Heap is empty");
}
T retval;
PriorityQueueHandle myhandle;
if (size == 1)
{
size = 0;
retval = heap[0].first;
myhandle = heap[0].firsthandle;
if (myhandle != null)
{
myhandle.index = -1;
}
heap[0].first = default(T);
heap[0].firsthandle = null;
}
else
{
retval = heap[0].last;
myhandle = heap[0].lasthandle;
if (myhandle != null)
{
myhandle.index = -1;
}
int lastcell = (size - 1) / 2;
if (size % 2 == 0)
{
updateLast(0, heap[lastcell].last, heap[lastcell].lasthandle);
heap[lastcell].last = default(T);
heap[lastcell].lasthandle = null;
}
else
{
updateLast(0, heap[lastcell].first, heap[lastcell].firsthandle);
heap[lastcell].first = default(T);
heap[lastcell].firsthandle = null;
}
size--;
heapifyMax(0);
}
handle = myhandle;
return(retval);
}
/// <summary>
/// Get or set the item corresponding to a handle.
/// </summary>
/// <param name="handle">The reference into the heap</param>
/// <returns></returns>
public T this[PriorityQueueHandle handle]
{
get
{
int cell;
bool isfirst;
checkHandle(handle, out cell, out isfirst);
return(isfirst ? heap[cell].first : heap[cell].last);
}
set
{
Replace(handle, value);
}
}
/// <summary>
/// Add an item to the priority queue, receiving a
/// handle for the item in the queue,
/// or reusing an already existing handle.
/// </summary>
/// <param name="handle">On output: a handle for the added item.
/// On input: null for allocating a new handle, an invalid handle for reuse.
/// A handle for reuse must be compatible with this priority queue,
/// by being created by a priority queue of the same runtime type, but not
/// necessarily the same priority queue object.</param>
/// <param name="item">The item to add.</param>
/// <returns>True since item will always be added unless the call throws an exception.</returns>
public bool Add(ref PriorityQueueHandle handle, T item)
{
PriorityQueueHandle myhandle = handle;
if (myhandle == null)
{
handle = myhandle = new PriorityQueueHandle();
}
else
if (myhandle.index != -1)
{
throw new ArgumentException("Handle not valid for reuse");
}
if (add(myhandle, item))
{
return(true);
}
return(false);
}
private PriorityQueueHandle checkHandle(PriorityQueueHandle handle, out int cell, out bool isfirst)
{
PriorityQueueHandle myhandle = handle;
int toremove = myhandle.index;
cell = toremove / 2;
isfirst = toremove % 2 == 0;
{
if (toremove == -1 || toremove >= size)
{
throw new ArgumentException("Invalid handle, index out of range");
}
PriorityQueueHandle actualhandle = isfirst ? heap[cell].firsthandle : heap[cell].lasthandle;
if (actualhandle != myhandle)
{
throw new ArgumentException("Invalid handle, doesn't match queue");
}
}
return(myhandle);
}
/// <summary>
/// Delete an item with a handle from a priority queue.
/// </summary>
/// <param name="handle">The handle for the item. The handle will be invalidated, but reusable.</param>
/// <returns>The deleted item</returns>
public T Delete(PriorityQueueHandle handle)
{
int cell;
bool isfirst;
PriorityQueueHandle myhandle = checkHandle(handle, out cell, out isfirst);
T retval;
myhandle.index = -1;
int lastcell = (size - 1) / 2;
if (cell == lastcell)
{
if (isfirst)
{
retval = heap[cell].first;
if (size % 2 == 0)
{
updateFirst(cell, heap[cell].last, heap[cell].lasthandle);
heap[cell].last = default(T);
heap[cell].lasthandle = null;
}
else
{
heap[cell].first = default(T);
heap[cell].firsthandle = null;
}
}
else
{
retval = heap[cell].last;
heap[cell].last = default(T);
heap[cell].lasthandle = null;
}
size--;
}
else if (isfirst)
{
retval = heap[cell].first;
if (size % 2 == 0)
{
updateFirst(cell, heap[lastcell].last, heap[lastcell].lasthandle);
heap[lastcell].last = default(T);
heap[lastcell].lasthandle = null;
}
else
{
updateFirst(cell, heap[lastcell].first, heap[lastcell].firsthandle);
heap[lastcell].first = default(T);
heap[lastcell].firsthandle = null;
}
size--;
if (heapifyMin(cell))
{
bubbleUpMax(cell);
}
else
{
bubbleUpMin(cell);
}
}
else
{
retval = heap[cell].last;
if (size % 2 == 0)
{
updateLast(cell, heap[lastcell].last, heap[lastcell].lasthandle);
heap[lastcell].last = default(T);
heap[lastcell].lasthandle = null;
}
else
{
updateLast(cell, heap[lastcell].first, heap[lastcell].firsthandle);
heap[lastcell].first = default(T);
heap[lastcell].firsthandle = null;
}
size--;
if (heapifyMax(cell))
{
bubbleUpMin(cell);
}
else
{
bubbleUpMax(cell);
}
}
return(retval);
}
/// <summary>
/// Remove the largest item from this priority queue.
/// </summary>
/// <returns>The removed item.</returns>
public T DeleteMax()
{
PriorityQueueHandle handle = null;
return(DeleteMax(out handle));
}
bool heapifyMax(int i)
{
bool swappedroot = false;
int cell = i, currentmax = cell;
T currentitem = heap[cell].last;
PriorityQueueHandle currenthandle = heap[cell].lasthandle;
if (i > 0)
{
T other = heap[cell].first;
if (comparer.Compare(currentitem, other) < 0)
{
swappedroot = true;
PriorityQueueHandle otherhandle = heap[cell].firsthandle;
updateFirst(cell, currentitem, currenthandle);
currentitem = other;
currenthandle = otherhandle;
}
}
T maxitem = currentitem;
PriorityQueueHandle maxhandle = currenthandle;
while (true)
{
int l = 2 * cell + 1, r = l + 1;
T lv, rv;
if (2 * l + 1 < size && comparer.Compare(lv = heap[l].last, maxitem) > 0)
{
currentmax = l; maxitem = lv;
}
if (2 * r + 1 < size && comparer.Compare(rv = heap[r].last, maxitem) > 0)
{
currentmax = r; maxitem = rv;
}
if (currentmax == cell)
{
break;
}
maxhandle = heap[currentmax].lasthandle;
updateLast(cell, maxitem, maxhandle);
cell = currentmax;
//Maybe swap first and last
T other = heap[cell].first;
if (comparer.Compare(currentitem, other) < 0)
{
PriorityQueueHandle otherhandle = heap[cell].firsthandle;
updateFirst(cell, currentitem, currenthandle);
currentitem = other;
currenthandle = otherhandle;
}
maxitem = currentitem;
maxhandle = currenthandle;
}
if (cell != i || swappedroot) //Check could be better?
{
updateLast(cell, maxitem, maxhandle);
}
return(swappedroot);
}
bool heapifyMin(int i)
{
bool swappedroot = false;
int cell = i, currentmin = cell;
T currentitem = heap[cell].first;
PriorityQueueHandle currenthandle = heap[cell].firsthandle;
if (i > 0)
{
T other = heap[cell].last;
if (2 * cell + 1 < size && comparer.Compare(currentitem, other) > 0)
{
swappedroot = true;
PriorityQueueHandle otherhandle = heap[cell].lasthandle;
updateLast(cell, currentitem, currenthandle);
currentitem = other;
currenthandle = otherhandle;
}
}
T minitem = currentitem;
PriorityQueueHandle minhandle = currenthandle;
while (true)
{
int l = 2 * cell + 1, r = l + 1;
T lv, rv;
if (2 * l < size && comparer.Compare(lv = heap[l].first, minitem) < 0)
{
currentmin = l; minitem = lv;
}
if (2 * r < size && comparer.Compare(rv = heap[r].first, minitem) < 0)
{
currentmin = r; minitem = rv;
}
if (currentmin == cell)
{
break;
}
minhandle = heap[currentmin].firsthandle;
updateFirst(cell, minitem, minhandle);
cell = currentmin;
//Maybe swap first and last
T other = heap[cell].last;
if (2 * currentmin + 1 < size && comparer.Compare(currentitem, other) > 0)
{
PriorityQueueHandle otherhandle = heap[cell].lasthandle;
updateLast(cell, currentitem, currenthandle);
currentitem = other;
currenthandle = otherhandle;
}
minitem = currentitem;
minhandle = currenthandle;
}
if (cell != i || swappedroot)
{
updateFirst(cell, minitem, minhandle);
}
return(swappedroot);
}