private void PercolateDown(int hole)
{
PriorityQueueElement obj = data[hole];
while ((hole * 2 + 1) < data.Count)
{
int child = hole * 2 + 1;
if (child != data.Count - 1)
{
if (data[child + 1].CompareTo(data[child]) < 0)
{
child++;
}
}
PriorityQueueElement childObj = data[child];
if (childObj.CompareTo(obj) < 0)
{
data[hole] = childObj;
childObj.PQIndex = hole;
hole = child;
}
else
{
break;
}
}
data[hole] = obj;
obj.PQIndex = hole;
}
// code from https://visualstudiomagazine.com/articles/2012/11/01/priority-queues-with-c/listing4.aspx
public virtual T Dequeue()
{
// assumes pq is not empty; up to calling code
int li = data.Count - 1; // last index (before removal)
PriorityQueueElement <T> frontItem = data[0]; // fetch the front
data[0] = data[li];
data.RemoveAt(li);
--li; // last index (after removal)
int pi = 0; // parent index. start at front of pq
while (true)
{
int ci = pi * 2 + 1; // left child index of parent
if (ci > li)
{
break; // no children so done
}
int rc = ci + 1; // right child
if (rc <= li && data[rc].ComparePriority(data[ci]) < 0) // if there is a rc (ci + 1), and it is smaller than left child, use the rc instead
{
ci = rc;
}
if (data[pi].ComparePriority(data[ci]) <= 0)
{
break; // parent is smaller than (or equal to) smallest child so done
}
PriorityQueueElement <T> tmp = data[pi];
data[pi] = data[ci];
data[ci] = tmp; // swap parent and child
pi = ci;
}
return(frontItem.item);
}
public void Insert(PriorityQueueElement e)
{
e.index = n;
heap[n] = e;
n++;
up(n - 1);
}
void swap(int i, int j)
{
PriorityQueueElement temp = heap[i];
heap[i] = heap[j];
heap[j] = temp;
heap[i].index = i;
heap[j].index = j;
}
// this dequeue method results in queue 'travelling' in memory as it grows and items are popped
public T DequeueBad()
{
if (IsEmpty())
{
throw new IndexOutOfRangeException("Priority Queue: attempting to pop from an empty queue.");
}
PriorityQueueElement <T> item = data[0];
data.RemoveAt(0);
return(item.item);
}
public void Insert(PriorityQueueElement obj)
{
int hole = data.Count;
data.Add(obj);
while (hole>0 && obj.CompareTo(data[(hole-1)/2])<0)
{
data[hole] = data[(hole-1)/2];
data[hole].PQIndex = hole;
hole = (hole-1) / 2;
}
data[hole] = obj;
obj.PQIndex = hole;
}
public void Insert(PriorityQueueElement obj)
{
int hole = data.Count;
data.Add(obj);
while (hole > 0 && obj.CompareTo(data[(hole - 1) / 2]) < 0)
{
data[hole] = data[(hole - 1) / 2];
data[hole].PQIndex = hole;
hole = (hole - 1) / 2;
}
data[hole] = obj;
obj.PQIndex = hole;
}
public int CompareTo(PriorityQueueElement other)
{
ManifoldPoint rec = other as ManifoldPoint;
if (this.distance < rec.distance)
{
return(-1);
}
if (this.distance > rec.distance)
{
return(1);
}
return(0);
}
public int CompareTo(PriorityQueueElement other)
{
NODE rec = other as NODE;
if (this.distance < rec.distance)
{
return(-1);
}
if (this.distance > rec.distance)
{
return(1);
}
return(0);
}
// for priority queue
public int ComparePriority(PriorityQueueElement <T> pt)
{
if (this.priority < pt.priority)
{
return(-1);
}
else if (this.priority == pt.priority)
{
return(0);
}
else
{
return(1);
}
}
private void PercolateUp(int hole)
{
PriorityQueueElement obj = data[hole];
while (hole > 0 && obj.CompareTo(data[(hole - 1) / 2]) < 0)
{
int parent = (hole - 1) / 2;
PriorityQueueElement parentObj = data[parent];
data[hole] = data[parent];
parentObj.PQIndex = hole;
hole = parent;
}
data[hole] = obj;
obj.PQIndex = hole;
}
public PriorityQueueElement DeleteMin()
{
if (IsEmpty())
{
throw new Exception();
}
PriorityQueueElement obj = data[0];
data[0] = data[data.Count - 1];
data.RemoveAt(data.Count - 1);
if (data.Count > 0)
{
data[0].PQIndex = 0;
PercolateDown(0);
}
return(obj);
}
// adds highest priority in the end
// code from: https://visualstudiomagazine.com/articles/2012/11/01/priority-queues-with-c/listing3.aspx
public virtual void Enqueue(T item, float priority)
{
PriorityQueueElement <T> pqe = new PriorityQueueElement <T>(item, priority);
// add item
data.Add(pqe);
int ci = data.Count - 1;
// swap items to maintain priority
while (ci > 0)
{
int pi = (ci - 1) / 2;
if (data[ci].ComparePriority(data[pi]) >= 0)
{
break;
}
PriorityQueueElement <T> tmp = data[ci];
data[ci] = data[pi];
data[pi] = tmp;
ci = pi;
}
}
public void Update(PriorityQueueElement obj)
{
PercolateUp(obj.PQIndex);
PercolateDown(obj.PQIndex);
}
public void Update(PriorityQueueElement obj)
{
PercolateUp(obj.PQIndex);
PercolateDown(obj.PQIndex);
}
