func NewLazyPrimMst(g weighted.EdgeWeightedGraph) LazyPrimMst {
l := LazyPrimMst{
marked: make([]bool, g.Vertices()),
mst: collections.Queue{},
pq: collections.PriorityQueue{}}
l.visit(g, 0)
for !l.pq.IsEmpty() {
e := l.pq.DelMin().(*weighted.Edge)
v := e.From()
w := e.OtherVertex(v)
if l.marked[v] && l.marked[w] {
continue
}
l.mst.Push(e)
if !l.marked[v] {
l.visit(g, v)
}
if !l.marked[w] {
l.visit(g, w)
}
}
return l
}
func (l *LazyPrimMst) visit(g weighted.EdgeWeightedGraph, v int) {
l.marked[v] = true
for _, e := range g.AdjacentTo(v) {
if !l.marked[e.OtherVertex(v)] {
l.pq.Insert(&e)
}
}
}
func (sp *DijkstraShortestPaths) visit(g weighted.EdgeWeightedGraph, v int) {
for _, e := range g.AdjacentTo(v) {
var w = e.To() // to because directed graph
totalWeighToVertex := sp.distTo[v] + e.Weight()
if sp.distTo[w] > totalWeighToVertex { //is new total weigh to the vertex is lower
sp.distTo[w] = totalWeighToVertex
sp.edgeTo[w] = e
if sp.pq.Contains(w) { //has lower weight than previous vertice
sp.pq.Change(w, sp.distTo[w])
} else { //there is no weight for the vertice
vertex := weighted.NewVertex(w, sp.distTo[w])
sp.pq.Insert(&vertex)
}
}
}
}
func (l *PrimMst) visit(g weighted.EdgeWeightedGraph, v int) {
l.marked[v] = true
//finds not visited lowest weight vertice
for _, e := range g.AdjacentTo(v) {
w := e.OtherVertex(v) //get vertex connected with the v vertex
if l.marked[w] { //vertice was already visited
continue
}
if e.Weight() < l.distTo[w] {
l.edgeTo[w] = e
l.distTo[w] = e.Weight()
if l.pq.Contains(w) { //has lower weight than previous vertice
l.pq.Change(w, l.distTo[w])
} else { //there is no weight for the vertice
vertex := weighted.NewVertex(w, l.distTo[w])
l.pq.Insert(&vertex)
}
}
}
}
func NewPrimMst(g weighted.EdgeWeightedGraph) PrimMst {
l := PrimMst{
marked: make([]bool, g.Vertices()),
edgeTo: make([]weighted.Edge, g.Vertices()),
distTo: make([]float32, g.Vertices()),
pq: collections.PriorityQueue{}}
for v := 0; v < g.Vertices(); v++ { //initialize all vertice distance weight to maximum
l.distTo[v] = math.MaxFloat32
}
l.distTo[0] = 0.0
vertex := weighted.NewVertex(0, 0.0)
l.pq.Insert(&vertex) //create zero index vertex with zero weight
for !l.pq.IsEmpty() {
vertex := l.pq.DelMin().(collections.IndexItem) // get lowest weight vertice from queue
l.visit(g, vertex.Index())
}
return l
}
func NewDijkstraShortestPaths(g weighted.EdgeWeightedGraph, from int) DijkstraShortestPaths {
l := DijkstraShortestPaths{
edgeTo: make([]weighted.Edge, g.Vertices()),
distTo: make([]float32, g.Vertices()),
pq: collections.PriorityQueue{},
from: from}
for v := 0; v < g.Vertices(); v++ { //initialize all vertice distance weight to maximum
l.distTo[v] = math.MaxFloat32
}
l.distTo[from] = 0.0
vertex := weighted.NewVertex(from, 0.0)
l.pq.Insert(&vertex) //create zero index vertex with zero weight
for l.pq.Len() > 0 {
indexItem := l.pq.DelMin().(collections.IndexItem) // get lowest weight vertice from queue
l.visit(g, indexItem.Index())
}
return l
}