1 | /* -*- C++ -*- |
---|
2 | * |
---|
3 | * This file is a part of LEMON, a generic C++ optimization library |
---|
4 | * |
---|
5 | * Copyright (C) 2003-2007 |
---|
6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
---|
7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
---|
8 | * |
---|
9 | * Permission to use, modify and distribute this software is granted |
---|
10 | * provided that this copyright notice appears in all copies. For |
---|
11 | * precise terms see the accompanying LICENSE file. |
---|
12 | * |
---|
13 | * This software is provided "AS IS" with no warranty of any kind, |
---|
14 | * express or implied, and with no claim as to its suitability for any |
---|
15 | * purpose. |
---|
16 | * |
---|
17 | */ |
---|
18 | |
---|
19 | ///\ingroup demos |
---|
20 | ///\file |
---|
21 | ///\brief Coloring of a graph. |
---|
22 | /// |
---|
23 | /// This example shows how can we color the nodes of a planar graph efficiently |
---|
24 | /// with six colors. |
---|
25 | /// |
---|
26 | /// \include coloring.cc |
---|
27 | |
---|
28 | #include <vector> |
---|
29 | |
---|
30 | #include <iostream> |
---|
31 | |
---|
32 | #include <lemon/smart_graph.h> |
---|
33 | #include <lemon/bucket_heap.h> |
---|
34 | #include <lemon/graph_reader.h> |
---|
35 | #include <lemon/graph_to_eps.h> |
---|
36 | |
---|
37 | #include <fstream> |
---|
38 | |
---|
39 | |
---|
40 | using namespace std; |
---|
41 | using namespace lemon; |
---|
42 | |
---|
43 | int main() { |
---|
44 | |
---|
45 | typedef SmartUGraph Graph; |
---|
46 | typedef Graph::Node Node; |
---|
47 | typedef Graph::NodeIt NodeIt; |
---|
48 | typedef Graph::UEdge UEdge; |
---|
49 | typedef Graph::IncEdgeIt IncEdgeIt; |
---|
50 | |
---|
51 | std::cout << "Six coloring of a planar graph" << std::endl; |
---|
52 | std::cout << "Input file: coloring.lgf" << std::endl; |
---|
53 | std::cout << "Output file: coloring.eps" << std::endl; |
---|
54 | |
---|
55 | Graph graph; |
---|
56 | |
---|
57 | UGraphReader<Graph> reader("coloring.lgf", graph); |
---|
58 | Graph::NodeMap<dim2::Point<double> > coords(graph); |
---|
59 | reader.readNodeMap("coords", coords); |
---|
60 | |
---|
61 | reader.run(); |
---|
62 | |
---|
63 | Graph::NodeMap<int> color(graph, -2); |
---|
64 | |
---|
65 | Graph::NodeMap<int> heapMap(graph, -1); |
---|
66 | BucketHeap<Graph::NodeMap<int> > heap(heapMap); |
---|
67 | |
---|
68 | for (NodeIt it(graph); it != INVALID; ++it) { |
---|
69 | heap.push(it, countOutEdges(graph, it)); |
---|
70 | } |
---|
71 | |
---|
72 | vector<Node> order; |
---|
73 | |
---|
74 | while (!heap.empty()) { |
---|
75 | Node node = heap.top(); |
---|
76 | heap.pop(); |
---|
77 | color[node] = -1; |
---|
78 | order.push_back(node); |
---|
79 | for (IncEdgeIt it(graph, node); it != INVALID; ++it) { |
---|
80 | Node target = graph.runningNode(it); |
---|
81 | if (color[target] == -2) { |
---|
82 | heap.decrease(target, heap[target] - 1); |
---|
83 | } |
---|
84 | } |
---|
85 | } |
---|
86 | |
---|
87 | for (int i = order.size() - 1; i >= 0; --i) { |
---|
88 | set<int> forbidden; |
---|
89 | for (IncEdgeIt it(graph, order[i]); it != INVALID; ++it) { |
---|
90 | Node target = graph.runningNode(it); |
---|
91 | if (color[target] != -1) { |
---|
92 | forbidden.insert(color[target]); |
---|
93 | } |
---|
94 | } |
---|
95 | int current = 0; |
---|
96 | while (forbidden.find(current) != forbidden.end()) ++current; |
---|
97 | color[order[i]] = current; |
---|
98 | } |
---|
99 | |
---|
100 | Palette palette; |
---|
101 | |
---|
102 | graphToEps(graph, "coloring.eps"). |
---|
103 | title("Six Colored Planar Graph"). |
---|
104 | copyright("(C) 2003-2007 LEMON Project"). |
---|
105 | coords(coords).nodeColors(composeMap(palette, color)). |
---|
106 | nodeScale(5.0).scaleToA4().run(); |
---|
107 | |
---|
108 | return 0; |
---|
109 | } |
---|