LEMON/LEMON-main Changeset - r707:3887d6f994d7

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Changeset - r707:3887d6f994d7

« 706:9314d9

708:5d313b »

r707:3887d6f994d7

Fri, 24 Jul 2009 01:07:45

[Not Reviewed]

0 comments (0 inline)

kpeter (Peter Kovacs)
kpeter@inf.elte.hu

Much faster implementation for BinomHeap (#301)

0 1 0

default

1 file changed with 88 insertions and 157 deletions:

lemon/binom_heap.h

157

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lemon/binom_heap.h

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@@ -76,15 +76,15 @@
 		      IN_HEAP = 0,    ///< = 0.
 		      PRE_HEAP = -1,  ///< = -1.
 		      POST_HEAP = -2  ///< = -2.
 		    };
 		  private:
-		    class store;
+		    class Store;
-		    std::vector<store> _data;
+		    std::vector<Store> _data;
 		    int _min, _head;
 		    ItemIntMap &_iim;
 		    Compare _comp;
 		    int _num_items;
 		  public:
@@ -153,29 +153,32 @@
 		    /// \pre \e item must not be stored in the heap.
 		    void push (const Item& item, const Prio& value) {
 		      int i=_iim[item];
 		      if ( i<0 ) {
 		        int s=_data.size();
 		        _iim.set( item,s );
-		        store st;
+		        Store st;
 		        st.name=item;
 		        st.prio=value;
 		        _data.push_back(st);
 		        i=s;
+		      }
 		      else {
 		        _data[i].parent=_data[i].right_neighbor=_data[i].child=-1;
 		        _data[i].degree=0;
 		        _data[i].in=true;
 		        _data[i].prio=value;
+		      }
 		      _data[i].prio=value;
 		      if( 0==_num_items ) { _head=i; _min=i; }
 		      else { merge(i); }
 		      _min = findMin();
+		      if( 0==_num_items ) {
 		        _head=i;
 		        _min=i;
 		      } else {
 		        merge(i);
 		        if( _comp(_data[i].prio, _data[_min].prio) ) _min=i;
+		      }
 		      ++_num_items;
+		    }
 		    /// \brief Return the item having minimum priority.
 		    ///
 		    /// This function returns the item having minimum priority.
@@ -205,32 +208,29 @@
 		      _data[_min].in=false;
 		      int head_child=-1;
 		      if ( _data[_min].child!=-1 ) {
 		        int child=_data[_min].child;
 		        int neighb;
 		        int prev=-1;
 		        while( child!=-1 ) {
 		          neighb=_data[child].right_neighbor;
 		          _data[child].parent=-1;
-		          _data[child].right_neighbor=prev;
+		          _data[child].right_neighbor=head_child;
 		          head_child=child;
 		          prev=child;
 		          child=neighb;
+		        }
+		      }
 		      // The first case is that there are only one root.
 		      if ( -1==_data[_head].right_neighbor ) {
 		      if ( _data[_head].right_neighbor==-1 ) {
 		        // there was only one root
 		        _head=head_child;
+		      }
 		      // The case where there are more roots.
 		      else {
 		        // there were more roots
 		        if( _head!=_min )  { unlace(_min); }
 		        else { _head=_data[_head].right_neighbor; }
 		        merge(head_child);
+		      }
 		      _min=findMin();
 		      --_num_items;
+		    }
@@ -253,79 +253,26 @@
 		    /// This function decreases the priority of an item to the given value.
 		    /// \param item The item.
 		    /// \param value The priority.
 		    /// \pre \e item must be stored in the heap with priority at least \e value.
 		    void decrease (Item item, const Prio& value) {
 		      int i=_iim[item];
 		      if( _comp( value,_data[i].prio ) ) {
 		        _data[i].prio=value;
 		        int p_loc=_data[i].parent, loc=i;
 		        int parent, child, neighb;
 		        while( -1!=p_loc && _comp(_data[loc].prio,_data[p_loc].prio) ) {
 		          // parent set for other loc_child
 		          child=_data[loc].child;
 		          while( -1!=child ) {
 		            _data[child].parent=p_loc;
 		            child=_data[child].right_neighbor;
+		          }
 		          // parent set for other p_loc_child
 		          child=_data[p_loc].child;
 		          while( -1!=child ) {
 		            _data[child].parent=loc;
 		            child=_data[child].right_neighbor;
+		          }
 		          child=_data[p_loc].child;
 		          _data[p_loc].child=_data[loc].child;
 		          if( child==loc )
 		            child=p_loc;
 		          _data[loc].child=child;
 		          // left_neighb set for p_loc
 		          if( _data[loc].child!=p_loc ) {
 		            while( _data[child].right_neighbor!=loc )
 		              child=_data[child].right_neighbor;
 		            _data[child].right_neighbor=p_loc;
+		          }
 		          // left_neighb set for loc
 		          parent=_data[p_loc].parent;
 		          if( -1!=parent ) child=_data[parent].child;
 		          else child=_head;
 		          if( child!=p_loc ) {
 		            while( _data[child].right_neighbor!=p_loc )
 		              child=_data[child].right_neighbor;
 		            _data[child].right_neighbor=loc;
+		          }
 		          neighb=_data[p_loc].right_neighbor;
 		          _data[p_loc].right_neighbor=_data[loc].right_neighbor;
 		          _data[loc].right_neighbor=neighb;
 		          _data[p_loc].parent=loc;
 		          _data[loc].parent=parent;
 		          if( -1!=parent && _data[parent].child==p_loc )
 		            _data[parent].child=loc;
 		          /*if new parent will be the first root*/
 		          if( _head==p_loc )
 		            _head=loc;
 		          p_loc=_data[loc].parent;
+		        }
+		      int p=_data[i].parent;
 		      _data[i].prio=value;
 		      while( p!=-1 && _comp(value, _data[p].prio) ) {
 		        _data[i].name=_data[p].name;
 		        _data[i].prio=_data[p].prio;
 		        _data[p].name=item;
 		        _data[p].prio=value;
 		        _iim[_data[i].name]=i;
 		        i=p;
 		        p=_data[p].parent;
+		      }
 		      if( _comp(value,_data[_min].prio) ) {
 		        _min=i;
+		      }
+		      _iim[item]=i;
 		      if ( _comp(value, _data[_min].prio) ) _min=i;
+		    }
 		    /// \brief Increase the priority of an item to the given value.
 		    ///
 		    /// This function increases the priority of an item to the given value.
 		    /// \param item The item.
@@ -372,142 +319,126 @@
 		      case IN_HEAP:
 		        break;
+		      }
+		    }
 		  private:
 		    // Find the minimum of the roots
 		    int findMin() {
 		      int min_loc=-1, min_val;
 		      int x=_head;
 		      if( x!=-1 ) {
 		        min_val=_data[x].prio;
 		        min_loc=x;
 		        x=_data[x].right_neighbor;
 		        while( x!=-1 ) {
 		      if( _head!=-1 ) {
 		        int min_loc=_head, min_val=_data[_head].prio;
 		        for( int x=_data[_head].right_neighbor; x!=-1;
 		             x=_data[x].right_neighbor ) {
 		          if( _comp( _data[x].prio,min_val ) ) {
 		            min_val=_data[x].prio;
 		            min_loc=x;
+		          }
 		          x=_data[x].right_neighbor;
+		        }
 		        return min_loc;
+		      }
-		      return min_loc;
+		      else return -1;
+		    }
 		    // Merge the heap with another heap starting at the given position
 		    void merge(int a) {
 		      interleave(a);
 		      if( _head==-1 || a==-1 ) return;
 		      if( _data[a].right_neighbor==-1 &&
 		          _data[a].degree<=_data[_head].degree ) {
 		        _data[a].right_neighbor=_head;
 		        _head=a;
 		      } else {
 		        interleave(a);
+		      }
 		      if( _data[_head].right_neighbor==-1 ) return;
 		      int x=_head;
 		      if( -1!=x ) {
 		        int x_prev=-1, x_next=_data[x].right_neighbor;
 		        while( -1!=x_next ) {
 		          if( _data[x].degree!=_data[x_next].degree || ( -1!=_data[x_next].right_neighbor && _data[_data[x_next].right_neighbor].degree==_data[x].degree ) ) {
-		            x_prev=x;
+		      int x_prev=-1, x_next=_data[x].right_neighbor;
 		      while( x_next!=-1 ) {
 		        if( _data[x].degree!=_data[x_next].degree ||
 		            ( _data[x_next].right_neighbor!=-1 &&
 		              _data[_data[x_next].right_neighbor].degree==_data[x].degree ) ) {
 		          x_prev=x;
 		          x=x_next;
+		        }
 		        else {
 		          if( _comp(_data[x_next].prio,_data[x].prio) ) {
 		            if( x_prev==-1 ) {
 		              _head=x_next;
 		            } else {
 		              _data[x_prev].right_neighbor=x_next;
+		            }
 		            fuse(x,x_next);
 		            x=x_next;
+		          }
 		          else {
 		            if( _comp(_data[x].prio,_data[x_next].prio) ) {
 		              _data[x].right_neighbor=_data[x_next].right_neighbor;
 		              fuse(x_next,x);
+		            }
 		            else {
 		              if( -1==x_prev ) { _head=x_next; }
 		              else {
 		                _data[x_prev].right_neighbor=x_next;
+		              }
 		              fuse(x,x_next);
 		              x=x_next;
+		            }
 		            _data[x].right_neighbor=_data[x_next].right_neighbor;
 		            fuse(x_next,x);
+		          }
 		          x_next=_data[x].right_neighbor;
+		        }
 		        x_next=_data[x].right_neighbor;
+		      }
+		    }
 		    // Interleave the elements of the given list into the list of the roots
 		    void interleave(int a) {
 		      int other=-1, head_other=-1;
 		      while( -1!=a || -1!=_head ) {
 		        if( -1==a ) {
 		          if( -1==head_other ) {
 		            head_other=_head;
+		          }
 		          else {
 		            _data[other].right_neighbor=_head;
+		          }
 		          _head=-1;
+		        }
 		        else if( -1==_head ) {
 		          if( -1==head_other ) {
 		            head_other=a;
+		          }
 		          else {
 		            _data[other].right_neighbor=a;
+		          }
 		          a=-1;
 		      int p=_head, q=a;
 		      int curr=_data.size();
 		      _data.push_back(Store());
 		      while( p!=-1 || q!=-1 ) {
 		        if( q==-1 || ( p!=-1 && _data[p].degree<_data[q].degree ) ) {
 		          _data[curr].right_neighbor=p;
 		          curr=p;
 		          p=_data[p].right_neighbor;
+		        }
 		        else {
 		          if( _data[a].degree<_data[_head].degree ) {
 		            if( -1==head_other ) {
 		              head_other=a;
+		            }
 		            else {
 		              _data[other].right_neighbor=a;
+		            }
 		            other=a;
 		            a=_data[a].right_neighbor;
+		          }
 		          else {
 		            if( -1==head_other ) {
 		              head_other=_head;
+		            }
 		            else {
 		              _data[other].right_neighbor=_head;
+		            }
 		            other=_head;
 		            _head=_data[_head].right_neighbor;
+		          }
 		          _data[curr].right_neighbor=q;
 		          curr=q;
 		          q=_data[q].right_neighbor;
+		        }
+		      }
-		      _head=head_other;
 		      _head=_data.back().right_neighbor;
 		      _data.pop_back();
+		    }
-		    // Lacing a under b
+		    // Lace node a under node b
 		    void fuse(int a, int b) {
 		      _data[a].parent=b;
 		      _data[a].right_neighbor=_data[b].child;
 		      _data[b].child=a;
 		      ++_data[b].degree;
+		    }
-		    // It is invoked only if a has siblings.
+		    // Unlace node a (if it has siblings)
 		    void unlace(int a) {
 		      int neighb=_data[a].right_neighbor;
 		      int other=_head;
 		      while( _data[other].right_neighbor!=a )
 		        other=_data[other].right_neighbor;
 		      _data[other].right_neighbor=neighb;
+		    }
 		  private:
-		    class store {
+		    class Store {
 		      friend class BinomHeap;
 		      Item name;
 		      int parent;
 		      int right_neighbor;
 		      int child;
 		      int degree;
 		      bool in;
 		      Prio prio;
-		      store() : parent(-1), right_neighbor(-1), child(-1), degree(0), in(true) {}
+		      Store() : parent(-1), right_neighbor(-1), child(-1), degree(0),
 		        in(true) {}
 		    };
 		  };
 		} //namespace lemon
 		#endif //LEMON_BINOM_HEAP_H

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