func NewColorHeap(src *graph.Node) Heap {
h := Heap{Items: make([]Heaper, graph.NumColors-1)}
for i := int(graph.Blank + 1); i < graph.NumColors; i++ {
h.Items[i-1] = ColorItem{
Color: graph.NodeColor(i),
}
}
for _, adj := range src.Adj {
if adj.Color == graph.Blank {
for i := graph.Blank + 1; i < graph.NumColors; i++ {
priority := h.Items[i-1].(ColorItem)
priority.Priority += adj.TakenColors[i]
h.Items[i-1] = priority
}
}
}
heap.Init(&h)
return h
}
// Setup for graph coloring backtracking algorithm,
// search heuristics are set based on heuristc flag
func colorMap(g graph.Graph) bool {
// For MRV, we'll use a heap
var h nh.Heap
if Heuristic.MRV {
h = nh.NewNodeHeap(len(g), Heuristic.Degree)
for _, n := range g {
h.Items = append(h.Items, nh.NewNodeItem(n))
}
heap.Init(&h)
}
// Init colors cache
ColorsCache.Colors = make([][]graph.NodeColor, len(g))
for i := range g {
ColorsCache.Colors[i] = make([]graph.NodeColor, 0, graph.NumColors-1)
for color := graph.Blank + 1; color < graph.NumColors; color++ {
ColorsCache.Colors[i] = append(ColorsCache.Colors[i], graph.NodeColor(color))
}
}
return colorMapBacktrack(g, 0, &h)
}