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1 | // (C) Copyright Jeremy Siek 2004 |
2 | // Distributed under the Boost Software License, Version 1.0. (See | |
3 | // accompanying file LICENSE_1_0.txt or copy at | |
4 | // http://www.boost.org/LICENSE_1_0.txt) | |
5 | ||
6 | #ifndef BOOST_DETAIL_DISJOINT_SETS_HPP | |
7 | #define BOOST_DETAIL_DISJOINT_SETS_HPP | |
8 | ||
9 | namespace boost { | |
10 | ||
11 | namespace detail { | |
12 | ||
13 | template <class ParentPA, class Vertex> | |
14 | Vertex | |
15 | find_representative_with_path_halving(ParentPA p, Vertex v) | |
16 | { | |
17 | Vertex parent = get(p, v); | |
18 | Vertex grandparent = get(p, parent); | |
19 | while (parent != grandparent) { | |
20 | put(p, v, grandparent); | |
21 | v = grandparent; | |
22 | parent = get(p, v); | |
23 | grandparent = get(p, parent); | |
24 | } | |
25 | return parent; | |
26 | } | |
27 | ||
28 | template <class ParentPA, class Vertex> | |
29 | Vertex | |
30 | find_representative_with_full_compression(ParentPA parent, Vertex v) | |
31 | { | |
32 | Vertex old = v; | |
33 | Vertex ancestor = get(parent, v); | |
34 | while (ancestor != v) { | |
35 | v = ancestor; | |
36 | ancestor = get(parent, v); | |
37 | } | |
38 | v = get(parent, old); | |
39 | while (ancestor != v) { | |
40 | put(parent, old, ancestor); | |
41 | old = v; | |
42 | v = get(parent, old); | |
43 | } | |
44 | return ancestor; | |
45 | } | |
46 | ||
47 | /* the postcondition of link sets is: | |
48 | component_representative(i) == component_representative(j) | |
49 | */ | |
50 | template <class ParentPA, class RankPA, class Vertex, | |
51 | class ComponentRepresentative> | |
52 | inline void | |
53 | link_sets(ParentPA p, RankPA rank, Vertex i, Vertex j, | |
54 | ComponentRepresentative comp_rep) | |
55 | { | |
56 | i = comp_rep(p, i); | |
57 | j = comp_rep(p, j); | |
58 | if (i == j) return; | |
59 | if (get(rank, i) > get(rank, j)) | |
60 | put(p, j, i); | |
61 | else { | |
62 | put(p, i, j); | |
63 | if (get(rank, i) == get(rank, j)) | |
64 | put(rank, j, get(rank, j) + 1); | |
65 | } | |
66 | } | |
67 | ||
68 | // normalize components has the following postcondidition: | |
69 | // i >= p[i] | |
70 | // that is, the representative is the node with the smallest index in its class | |
71 | // as its precondition it it assumes that the node container is compressed | |
72 | ||
73 | template <class ParentPA, class Vertex> | |
74 | inline void | |
75 | normalize_node(ParentPA p, Vertex i) | |
76 | { | |
77 | if (i > get(p,i) || get(p, get(p,i)) != get(p,i)) | |
78 | put(p,i, get(p, get(p,i))); | |
79 | else { | |
80 | put(p, get(p,i), i); | |
81 | put(p, i, i); | |
82 | } | |
83 | } | |
84 | ||
85 | } // namespace detail | |
86 | } // namespace boost | |
87 | ||
88 | #endif // BOOST_DETAIL_DISJOINT_SETS_HPP |