#### /Src/Dependencies/Boost/boost/graph/sequential_vertex_coloring.hpp

C++ Header | 124 lines | 65 code | 17 blank | 42 comment | 12 complexity | 4845de2fa259990ff89f50f8a03046a0 MD5 | raw file
```  1//=======================================================================
2// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
3// Copyright 2004 The Trustees of Indiana University
4// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
5//
7// accompanying file LICENSE_1_0.txt or copy at
9//=======================================================================
10#ifndef BOOST_GRAPH_SEQUENTIAL_VERTEX_COLORING_HPP
11#define BOOST_GRAPH_SEQUENTIAL_VERTEX_COLORING_HPP
12
13#include <vector>
14#include <boost/graph/graph_traits.hpp>
15#include <boost/tuple/tuple.hpp>
16#include <boost/property_map/property_map.hpp>
17#include <boost/limits.hpp>
18
19#ifdef BOOST_NO_TEMPLATED_ITERATOR_CONSTRUCTORS
20#  include <iterator>
21#endif
22
23/* This algorithm is to find coloring of a graph
24
25   Algorithm:
26   Let G = (V,E) be a graph with vertices (somehow) ordered v_1, v_2, ...,
27   v_n. For k = 1, 2, ..., n the sequential algorithm assigns v_k to the
28   smallest possible color.
29
30   Reference:
31
32   Thomas F. Coleman and Jorge J. More, Estimation of sparse Jacobian
33   matrices and graph coloring problems. J. Numer. Anal. V20, P187-209, 1983
34
35   v_k is stored as o[k] here.
36
37   The color of the vertex v will be stored in color[v].
38   i.e., vertex v belongs to coloring color[v] */
39
40namespace boost {
41  template <class VertexListGraph, class OrderPA, class ColorMap>
42  typename property_traits<ColorMap>::value_type
43  sequential_vertex_coloring(const VertexListGraph& G, OrderPA order,
44                             ColorMap color)
45  {
46    typedef graph_traits<VertexListGraph> GraphTraits;
47    typedef typename GraphTraits::vertex_descriptor Vertex;
48    typedef typename property_traits<ColorMap>::value_type size_type;
49
50    size_type max_color = 0;
51    const size_type V = num_vertices(G);
52
53    // We need to keep track of which colors are used by
54    // adjacent vertices. We do this by marking the colors
55    // that are used. The mark array contains the mark
56    // for each color. The length of mark is the
57    // number of vertices since the maximum possible number of colors
58    // is the number of vertices.
59    std::vector<size_type> mark(V,
60                                std::numeric_limits<size_type>::max BOOST_PREVENT_MACRO_SUBSTITUTION());
61
62    //Initialize colors
63    typename GraphTraits::vertex_iterator v, vend;
64    for (boost::tie(v, vend) = vertices(G); v != vend; ++v)
65      put(color, *v, V-1);
66
67    //Determine the color for every vertex one by one
68    for ( size_type i = 0; i < V; i++) {
69      Vertex current = get(order,i);
71
72      //Mark the colors of vertices adjacent to current.
73      //i can be the value for marking since i increases successively
74      for (boost::tie(v,vend) = adjacent_vertices(current, G); v != vend; ++v)
75        mark[get(color,*v)] = i;
76
77      //Next step is to assign the smallest un-marked color
78      //to the current vertex.
79      size_type j = 0;
80
81      //Scan through all useable colors, find the smallest possible
82      //color that is not used by neighbors.  Note that if mark[j]
83      //is equal to i, color j is used by one of the current vertex's
84      //neighbors.
85      while ( j < max_color && mark[j] == i )
86        ++j;
87
88      if ( j == max_color )  //All colors are used up. Add one more color
89        ++max_color;
90
91      //At this point, j is the smallest possible color
92      put(color, current, j);  //Save the color of vertex current
93    }
94
95    return max_color;
96  }
97
98  template<class VertexListGraph, class ColorMap>
99  typename property_traits<ColorMap>::value_type
100  sequential_vertex_coloring(const VertexListGraph& G, ColorMap color)
101  {
102    typedef typename graph_traits<VertexListGraph>::vertex_descriptor
103      vertex_descriptor;
104    typedef typename graph_traits<VertexListGraph>::vertex_iterator
105      vertex_iterator;
106
107    std::pair<vertex_iterator, vertex_iterator> v = vertices(G);
108#ifndef BOOST_NO_TEMPLATED_ITERATOR_CONSTRUCTORS
109    std::vector<vertex_descriptor> order(v.first, v.second);
110#else
111    std::vector<vertex_descriptor> order;
112    order.reserve(std::distance(v.first, v.second));
113    while (v.first != v.second) order.push_back(*v.first++);
114#endif
115    return sequential_vertex_coloring
116             (G,
117              make_iterator_property_map
118              (order.begin(), identity_property_map(),
119               graph_traits<VertexListGraph>::null_vertex()),
120              color);
121  }
122}
123
124#endif
```