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