コード例 #1
0
ファイル: has_cycle.cpp プロジェクト: alyssaq/graphs
bool Graph<Vertex, Edge_value>::Check_node_for_cycle(const Vertex& start_vertex, 
              set< Vertex, less<Vertex> >& processed,
              set< Vertex, less<Vertex> >& visited)
{
  if (processed.find(start_vertex) == processed.end()) {
    // We've not already processed this node in an earlier pass.
    // We now insert the vertex into the visited set.  The insert
    // method on sets returns a pair, the first of which is an
    // iterator pointing to the inserted item, and the second
    // of which is a boolean telling us whether the item was indeed
    // inserted, or whether it was already in the set.  We'll use
    // this boolean value to determine whether we'd already visited
    // this node, implying that we have a cycle.
    pair<set< Vertex, less<Vertex> >::iterator, bool> 
            insert_result(visited.insert(start_vertex));
    if (!insert_result.second) {
      // We've already visited this vertex on this pass, i.e.,
      // we have a cycle.
      return(true);
    } else {
      // We've not seen this node already.
      // Loop through the vertices that start_vertex has
      // edges going to, and make recursive calls for each of them.
      bool has_cycle = false;
      
      // A multimap can contain multiple pairs for the same key
      // (in our case, multiple edges leaving the same vertex).  The
      // multimap class has a member function equal_range that
      // returns a pair of iterators.  The first points to the
      // first item in the multiset with the given key (in our
      // case start_vertex), and the second points to the first
      // item _after_ the _last_ item with our given key.  Thus
      // one can loop starting at the first iterator and ending
      // at the second iterator, and get all the pairs that match
      // our key.
      pair<edge_set::iterator, edge_set::iterator> vertex_edge_bounds;
      vertex_edge_bounds = edges.equal_range(start_vertex);

      // Go through each edge from start_vertex, and recursively call
      // Check_node_for_cycle.
      edge_set::const_iterator i = vertex_edge_bounds.first;
      while (!has_cycle && i != vertex_edge_bounds.second) {
        has_cycle = has_cycle || Check_node_for_cycle((*i).second, processed, visited);
        ++i;
      }
      // We've now chased down every edge from start_vertex, so 
      // we'll add start_vertex to the set of processed vertices.
            processed.insert(start_vertex);
            // Remove start_vertex from the list of visited vertices.
            visited.erase(insert_result.first);
            return(has_cycle);
        }
    } else {
        // We've already been here, and there were no cycles from this
        // point.
        return(false);
    }
}
コード例 #2
0
 void reduce_core(goal_ref const& g, goal_ref_buffer& result) {
     init(g);
     m_context.push();
     assert_clauses(g);
     m_context.push();   // internalize assertions. 
     prune_clauses();
     goal_ref r(g);
     insert_result(r);
     r->elim_true();
     result.push_back(r.get());        
     m_context.pop(2);
     TRACE("unit_subsumption_tactic", g->display(tout); r->display(tout););
コード例 #3
0
ファイル: 03-123006.c プロジェクト: tiwanari/pro_exce
/**
 *  強度を計算する再帰関数
 *  @param ARRARY *first 最初の単語が格納された要素
 *  @param TREE *conb 2つの単語の要素
 *  @param int threshold 計算に用いる出現頻度の最小値
 *  @param double *get_indicator(ARRAY *, ARRAY *, TREE *) 強度を返す関数
 */
void calc_indicator_in_tree(ARRAY *first, TREE *conb, int threshold,
                            double (*get_indicator)(ARRAY *, ARRAY *, TREE *))
{
    double indicator;
    
    // 要素が登録されていない
    if (conb->left == conb || conb->right == conb)
        return ;
    
    if (conb->left != NULL)   // 右へ
        calc_indicator_in_tree(first, conb->left,  threshold, get_indicator);
    
    if (conb->right != NULL)  // 右へ
        calc_indicator_in_tree(first, conb->right, threshold, get_indicator);
    
    // 閾値よりも低い時は計算しない
    if (words[conb->id]->freq >= threshold)
    {
        // 強度の計算
        indicator = get_indicator(first, words[conb->id], conb);
        insert_result(first->word, words[conb->id]->word, indicator);   // 登録
    }
}