public List <int> dijkstra(int xf, int yf, int xt, int yt) //col , row ->> source , destination
{
// Data holders
double inf = helper.infinty();
int [] path = new int[size + 2];
double [] dis = new double[size + 2];
Priority_Queue q = new Priority_Queue(10);
int node = helper.flatten(xf, yf, width); // col , row
int to = helper.flatten(xt, yt, width); //col , row
//initialize
for (int i = 0; i <= size; i++)
{
dis[i] = inf;
}
dis[node] = 0;
path[node] = -1;
q.insert(node, 0);
while (!q.empty())
{
// pick clossest
node = q.top().id;
double dnode = q.top().w;
// delete
q.pop();
pixel tmp_pixel = helper.un_flatten(node, width);
// update the node that I relax from
xf = tmp_pixel.y; // col
yf = tmp_pixel.x; // row
if (node == to)
{
break;
}
if (dis[node] < dnode)
{
continue;
}
List <Tuple <int, double> > neighbours = new List <Tuple <int, double> >();
// build neghbours 4 connectivity
Vector2D v = ImageOperations.CalculatePixelEnergies(xf, yf, MainForm.ImageMatrix);
int tmp_id; // hold my child that I will add
double w;
if (helper.valid(xf, yf + 1)) // bellow
{
w = v.Y;
w = (double)1 / w;
w = helper.remove_infinty(w);
tmp_id = helper.flatten(xf, yf + 1, width);
neighbours.Add(Tuple.Create(tmp_id, w));
}
if (helper.valid(xf + 1, yf)) // to the right
{
w = v.X;
w = (double)1 / w;
w = helper.remove_infinty(w);
tmp_id = helper.flatten(xf + 1, yf, width);
neighbours.Add(Tuple.Create(tmp_id, w));
}
if (helper.valid(xf, yf - 1)) // above me
{
v = ImageOperations.CalculatePixelEnergies(xf, yf - 1, MainForm.ImageMatrix);
w = v.Y;
w = (double)1 / w;
w = helper.remove_infinty(w);
tmp_id = helper.flatten(xf, yf - 1, width);
neighbours.Add(Tuple.Create(tmp_id, w));
}
if (helper.valid(xf - 1, yf)) // to the left
{
v = ImageOperations.CalculatePixelEnergies(xf - 1, yf, MainForm.ImageMatrix);
w = v.X; // energy
w = (double)1 / w; // weight
w = helper.remove_infinty(w);
tmp_id = helper.flatten(xf - 1, yf, width);
neighbours.Add(Tuple.Create(tmp_id, w));
}
// relax
for (int i = 0; i < neighbours.Count; i++)
{
int child = neighbours[i].Item1;
double cost = neighbours[i].Item2;
if (dis[child] > dnode + cost)
{
dis[child] = dnode + cost;
path[child] = node; // your current parent
q.insert(child, dis[child]);
}
}
}
// build the path , we are always sure that we will reach our distination
List <int> shp = new List <int>();
shp.Add(to);
while (path[to] != -1)
{
shp.Add(path[to]);
to = path[to];
}
shp.Reverse();
return(shp);
}
/*
* shortest path algorithm ->>> Dijkstra
* scource is -> current_anchor_point
* destination is -> free_point
*
* we will use our p_q_min_heap as DS for selecting the clossest node
*/
public List <int> dijkstra(int f, int to)
{
// infinity
double inf = helper.infinty();
Priority_Queue q = new Priority_Queue(10); // size is number of nodes in the graph
int node = f;
int dist = to;
double[] distance = new double[size + 2];
int[] path = new int[size + 2];
// initialize
for (int i = 0; i < size; i++)
{
distance[i] = inf;
}
distance[node] = 0;
path[node] = -1; // no parent
q.insert(node, 0);
// end
while (!q.empty())
{
// pick clossest node
node = q.top().id;
double dnode = q.top().w;
// delete
q.pop();
// prunning
if (node == dist)
{
break;
}
if (dnode > distance[node])
{
continue;
}
// relax
for (int i = 0; i < g[node].Count; i++)
{
int child = g[node][i].Item1;
double cost = g[node][i].Item2;
if (distance[child] > dnode + cost)
{
distance[child] = dnode + cost;
path[child] = node;
q.insert(child, distance[child]);
}
}
}
/*
* construct the path
* order of the path don't matter
* cut it just draw throw them
*/
List <int> l = new List <int>();
l.Add(dist);
int tid = dist;
while (path[tid] != -1)
{
l.Add(path[tid]);
tid = path[tid]; // go back
}
//l.Reverse();
return(l);
}