1 //=======================================================================
2 // Copyright 2001 University of Notre Dame.
3 // Authors: Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee
4 //
5 // Distributed under the Boost Software License, Version 1.0. (See
6 // accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8 //=======================================================================
9
10 #include <stdio.h>
11 #include <iostream>
12 #include <boost/graph/stanford_graph.hpp>
13 #include <boost/graph/strong_components.hpp>
14
15 #define specs(v) \
16 (filename ? index_map[v] : v->cat_no) << " " << v->name
17
main(int argc,char * argv[])18 int main(int argc, char* argv[])
19 {
20 using namespace boost;
21 Graph* g;
22 typedef graph_traits<Graph*>::vertex_descriptor vertex_t;
23 unsigned long n = 0;
24 unsigned long d = 0;
25 unsigned long p = 0;
26 long s = 0;
27 char* filename = NULL;
28 int c, i;
29
30 while (--argc) {
31 if (sscanf(argv[argc], "-n%lu", &n) == 1);
32 else if (sscanf(argv[argc], "-d%lu", &d) == 1);
33 else if (sscanf(argv[argc], "-p%lu", &p) == 1);
34 else if (sscanf(argv[argc], "-s%ld", &s) == 1);
35 else if (strncmp(argv[argc], "-g", 2) == 0)
36 filename = argv[argc] + 2;
37 else {
38 fprintf(stderr, "Usage: %s [-nN][-dN][-pN][-sN][-gfoo]\n", argv[0]);
39 return -2;
40 }
41 }
42
43 g = (filename ? restore_graph(filename) : roget(n, d, p, s));
44 if (g == NULL) {
45 fprintf(stderr, "Sorry, can't create the graph! (error code %ld)\n",
46 panic_code);
47 return -1;
48 }
49 printf("Reachability analysis of %s\n\n", g->id);
50
51 // - The root map corresponds to what Knuth calls the "min" field.
52 // - The discover time map is the "rank" field
53 // - Knuth uses the rank field for double duty, to record the
54 // discover time, and to keep track of which vertices have
55 // been visited. The BGL strong_components() function needs
56 // a separate field for marking colors, so we use the w field.
57
58 std::vector<int> comp(num_vertices(g));
59 property_map<Graph*, vertex_index_t>::type
60 index_map = get(vertex_index, g);
61
62 property_map<Graph*, v_property<vertex_t> >::type
63 root = get(v_property<vertex_t>(), g);
64
65 int num_comp = strong_components
66 (g, make_iterator_property_map(comp.begin(), index_map),
67 root_map(root).
68 discover_time_map(get(z_property<long>(), g)).
69 color_map(get(w_property<long>(), g)));
70
71 std::vector< std::vector<vertex_t> > strong_comp(num_comp);
72
73 // First add representative vertices to each component's list
74 graph_traits<Graph*>::vertex_iterator vi, vi_end;
75 for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
76 if (root[*vi] == *vi)
77 strong_comp[comp[index_map[*vi]]].push_back(*vi);
78
79 // Then add the other vertices of the component
80 for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
81 if (root[*vi] != *vi)
82 strong_comp[comp[index_map[*vi]]].push_back(*vi);
83
84 // We do not print out the "from" and "to" information as Knuth
85 // does because we no longer have easy access to that information
86 // from outside the algorithm.
87
88 for (c = 0; c < num_comp; ++c) {
89 vertex_t v = strong_comp[c].front();
90 std::cout << "Strong component `" << specs(v) << "'";
91 if (strong_comp[c].size() > 1) {
92 std::cout << " also includes:\n";
93 for (i = 1; i < strong_comp[c].size(); ++i)
94 std::cout << " " << specs(strong_comp[c][i]) << std::endl;
95 } else
96 std::cout << std::endl;
97 }
98
99 // Next we print out the "component graph" or "condensation", that
100 // is, we consider each component to be a vertex in a new graph
101 // where there is an edge connecting one component to another if there
102 // is one or more edges connecting any of the vertices from the
103 // first component to any of the vertices in the second. We use the
104 // name of the representative vertex as the name of the component.
105
106 printf("\nLinks between components:\n");
107
108 // This array provides an efficient way to check if we've already
109 // created a link from the current component to the component
110 // of the target vertex.
111 std::vector<int> mark(num_comp, (std::numeric_limits<int>::max)());
112
113 // We go in reverse order just to mimic the output ordering in
114 // Knuth's version.
115 for (c = num_comp - 1; c >= 0; --c) {
116 vertex_t u = strong_comp[c][0];
117 for (i = 0; i < strong_comp[c].size(); ++i) {
118 vertex_t v = strong_comp[c][i];
119 graph_traits<Graph*>::out_edge_iterator ei, ei_end;
120 for (boost::tie(ei, ei_end) = out_edges(v, g); ei != ei_end; ++ei) {
121 vertex_t x = target(*ei, g);
122 int comp_x = comp[index_map[x]];
123 if (comp_x != c && mark[comp_x] != c) {
124 mark[comp_x] = c;
125 vertex_t w = strong_comp[comp_x][0];
126 std::cout << specs(u) << " -> " << specs(w)
127 << " (e.g., " << specs(v) << " -> " << specs(x) << ")\n";
128 } // if
129 } // for
130 } // for
131 } // for
132 }
133