func NewDijkstra(g *Graph, s int) *Dijkstra {
this := &Dijkstra{}
this.edgeTo = make([]Edge, g.V())
this.distTo = make([]algorithms.Double, g.V())
for v := 0; v < g.V(); v++ {
this.distTo[v] = algorithms.Double(math.Inf(1))
}
this.distTo[s] = 0.0
if NewCycle(g).HasCycle() {
this.cycle = true
this.pq = container.NewMinPriorityQueue(g.V())
this.pq.Push(&container.PriorityQueueItem{s, algorithms.Double(0.0)})
for !this.pq.IsEmpty() {
pqi := this.pq.Pop().Value.(*container.PriorityQueueItem)
this.relax(g, pqi.Index)
}
} else {
this.cycle = false
iter := NewDFO(g).ReversePost().Iterator()
for iter.HasNext() {
v := iter.Next().Value.(int)
this.relax(g, v)
}
}
return this
}
func NewGraphFromReader(r io.Reader, gt GraphType) *Graph {
var v, e, w int
var err error
var this *Graph
scanner := bufio.NewScanner(r)
scanner.Split(bufio.ScanWords)
scanner.Scan()
if v, err = strconv.Atoi(scanner.Text()); err != nil {
fmt.Printf(err.Error())
return nil
}
switch gt {
case DIGRAPH:
this = NewDigraph(v)
case EWDIGRAPH:
this = NewEWDigraph(v)
default:
this = NewUnigraph(v)
}
scanner.Scan()
if e, err = strconv.Atoi(scanner.Text()); err != nil {
fmt.Printf(err.Error())
return nil
}
for i := 0; i < e; i++ {
scanner.Scan()
if v, err = strconv.Atoi(scanner.Text()); err != nil {
fmt.Printf(err.Error())
return nil
}
scanner.Scan()
if w, err = strconv.Atoi(scanner.Text()); err != nil {
fmt.Printf(err.Error())
return nil
}
if gt == EWDIGRAPH {
var weight float64
scanner.Scan()
if weight, err = strconv.ParseFloat(scanner.Text(), 64); err != nil {
fmt.Printf(err.Error())
return nil
}
this.AddWeightedEdge(v, w, algorithms.Double(weight))
} else {
this.AddEdge(v, w)
}
}
return this
}
func (this *Dijkstra) HasPathTo(v int) bool {
return this.distTo[v] < algorithms.Double(math.Inf(1))
}