1 | // -*- c++ -*- |
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2 | #ifndef LEMON_BFS_DFS_MISC_H |
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3 | #define LEMON_BFS_DFS_MISC_H |
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4 | |
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5 | /// \ingroup galgs |
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6 | /// \file |
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7 | /// \brief Miscellaneous algorithms using bfs and dfs. |
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8 | /// |
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9 | /// This file contains several algorithms using bfs and dfs. |
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10 | /// |
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11 | // ///\author Marton Makai |
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12 | |
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13 | #include <bfs_dfs.h> |
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14 | #include <for_each_macros.h> |
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15 | |
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16 | namespace lemon { |
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17 | |
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18 | /// This function eats a read-write \c BoolMap& bool_map, |
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19 | /// which have to work well up |
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20 | /// to its \c set and \c operator[]() method. Thus we have to deal |
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21 | /// very carefully with an uninitialized \c IterableBoolMap. |
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22 | /// \ingroup galgs |
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23 | template<typename Graph, typename BoolMap> |
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24 | bool isBipartite(const Graph& g, BoolMap& bool_map) { |
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25 | typedef typename Graph::template NodeMap<bool> ReachedMap; |
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26 | ReachedMap reached(g/*, false*/); |
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27 | BfsIterator<Graph, ReachedMap> bfs(g, reached); |
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28 | FOR_EACH_LOC(typename Graph::NodeIt, n, g) { |
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29 | if (!reached[n]) { |
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30 | bfs.pushAndSetReached(n); |
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31 | bool_map.set(n, false); |
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32 | while (!bfs.finished()) { |
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33 | if (bfs.isBNodeNewlyReached()) { |
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34 | bool_map.set(bfs.bNode())=!bfs.aNode(); |
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35 | } else { |
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36 | if (bool_map[bfs.bNode()]==bool_map[bfs.aNode()]) { |
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37 | return false; |
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38 | } |
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39 | } |
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40 | ++bfs; |
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41 | } |
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42 | } |
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43 | } |
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44 | |
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45 | return true; |
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46 | } |
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47 | |
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48 | /// experimental topsort, |
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49 | /// I think the final version will work as an iterator |
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50 | /// if the graph is not a acyclic, the na pre-topological order is obtained |
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51 | /// (see Schrijver's book). |
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52 | /// PredMap have to be a writtable node-map. |
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53 | /// If the graph is directed and not acyclic, |
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54 | /// then going back from the returned node via the pred information, a |
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55 | /// cycle is obtained. |
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56 | /// \ingroup galgs |
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57 | template<typename Graph, typename PredMap> |
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58 | typename Graph::Node |
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59 | topSort(const Graph& g, std::list<typename Graph::Node>& l, |
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60 | PredMap& pred) { |
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61 | l.clear(); |
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62 | typedef typename Graph::template NodeMap<bool> ReachedMap; |
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63 | typedef typename Graph::template NodeMap<bool> ExaminedMap; |
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64 | ReachedMap reached(g/*, false*/); |
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65 | ExaminedMap examined(g/*, false*/); |
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66 | DfsIterator<Graph, ReachedMap> dfs(g, reached); |
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67 | FOR_EACH_LOC(typename Graph::NodeIt, n, g) { |
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68 | if (!reached[n]) { |
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69 | dfs.pushAndSetReached(n); |
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70 | pred.set(n, INVALID); |
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71 | while (!dfs.finished()) { |
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72 | ++dfs; |
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73 | if (dfs.isBNodeNewlyReached()) { |
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74 | ///\bug lemon 0.2-ben Edge kell |
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75 | pred.set(dfs.aNode(), typename Graph::OutEdgeIt(dfs)); |
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76 | } else { |
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77 | ///\bug ugyanaz |
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78 | if (g.valid(typename Graph::OutEdgeIt(dfs)) && |
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79 | !examined[dfs.bNode()]) { |
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80 | ///\bug lemon 0.2-ben Edge kell |
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81 | pred.set(dfs.bNode(), typename Graph::OutEdgeIt(dfs)); |
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82 | return dfs.aNode(); |
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83 | } |
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84 | } |
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85 | if (dfs.isANodeExamined()) { |
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86 | l.push_back(dfs.aNode()); |
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87 | examined.set(dfs.aNode(), true); |
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88 | } |
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89 | } |
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90 | } |
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91 | } |
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92 | return INVALID; |
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93 | } |
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94 | |
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95 | } //namespace lemon |
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96 | |
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97 | #endif //LEMON_BFS_DFS_MISC_H |
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