// -*- C++ -*-

 /*

  *template <typename Item, 

  *          typename Prio, 

  *          typename ItemIntMap, 

  *          typename Compare = std::less<Prio> >

  * 

  *constructors:

  *

  *FibHeap(ItemIntMap),   FibHeap(ItemIntMap, Compare)

  *

  *Member functions:

  *

  *int size() : returns the number of elements in the heap

  *

  *bool empty() : true iff size()=0

  *

  *void push(Item, Prio) : pushes Item to the heap with priority Prio. If

  *     Item was already in the heap, it calls decrease(Item, Prio) 

  *

  *Item top() : returns the Item with least Prio

  *

  *Prio prio() : returns the least Prio

  *  

  *Prio get(Item) : returns Prio of Item

  *

  *void pop() : deletes the Item with least Prio

  *

  *void erase(Item) : deletes Item from the heap if it was already there

  *

  *void decrease(Item, P) : If Item was not in the heap, then it calls 

  *     push(Item, P). If item is in the heap with Prio more than P

  *     then sets its Prio to P.

  *

  *void increase(Item, P) : If Item was not in the heap, then it calls 

  *     push(Item, P). If item is in the heap with Prio less than P

  *     then sets its Prio to P.

  *

  *

  *In Fibonacci heaps, increase and erase are not efficient, in case of

  *many calls to these operations, it is better to use bin_heap.

  */

 #ifndef FIB_HEAP_H

 #define FIB_HEAP_H

 #include <vector>

 #include <functional>

 #include <math.h>

 namespace hugo {

   template <typename Item, typename Prio, typename ItemIntMap, 

     typename Compare = std::less<Prio> >

   class FibHeap {

     typedef Prio PrioType;

     class store;

     std::vector<store> container;

     int minimum;

     bool blank;

     ItemIntMap &iimap;

     Compare comp;

   public :

     FibHeap(ItemIntMap &_iimap) : minimum(), blank(true), iimap(_iimap) {} 

     FibHeap(ItemIntMap &_iimap, const Compare &_comp) : minimum(), 

       blank(true), iimap(_iimap), comp(_comp) {}

     int size() const {

       int s=0;

       for ( unsigned int i=0; i!=container.size(); ++i )

 	if ( container[i].in ) ++s;

       return s; 

     }

    bool empty() const { return blank; }

    void push (Item const it, PrioType const value) 

    {

      int i=iimap.get(it);

      if ( i >= 0 && container[i].in ) decrease(it, value); 

      else {

        if ( i < 0 ) {

 	 int s=container.size();

 	 iimap.set( it, s );	

 	 store st;

 	 st.name=it;

 	 container.push_back(st);

 	 i=s;

        }

        if ( !blank ) {

 	 container[container[minimum].right_neighbor].left_neighbor=i;

 	 container[i].right_neighbor=container[minimum].right_neighbor;

 	 container[minimum].right_neighbor=i;

 	 container[i].left_neighbor=minimum;

 	 if ( !comp( container[minimum].prio, value) ) minimum=i; 

        } else {

 	 container[i].right_neighbor=container[i].left_neighbor=i;

 	 minimum=i;	

 	 blank=false;

        }

        container[i].prio=value;

      }

    }

     Item top() const {

       if ( !blank ) { 

 	return container[minimum].name;

       } else {

 	return Item();

       }

     }

     PrioType prio() const {

       if ( !blank ) { 

 	return container[minimum].prio;

       } else {

 	return PrioType();

       }

     }

     const PrioType get(const Item& it) const

     {

       int i=iimap.get(it);

       if ( i >= 0 && container[i].in ) { 

 	return container[i].prio;

       } else {

 	return PrioType();

       }

     }

     void pop() {

       if ( !blank ) {

 	/*The first case is that there are only one root.*/

 	if ( container[minimum].left_neighbor==minimum ) {

 	  container[minimum].in=false;

 	  if ( container[minimum].degree==0 ) blank=true; 

 	  else { 

 	    makeroot(container[minimum].child);

 	    minimum=container[minimum].child;

 	    balance();

 	  } 

        } else {

 	 int right=container[minimum].right_neighbor;

 	 unlace(minimum);

 	 container[minimum].in=false;

 	 if ( container[minimum].degree > 0 ) {

 	   int left=container[minimum].left_neighbor;

 	   int child=container[minimum].child;

 	   int last_child=container[child].left_neighbor;

 	   container[left].right_neighbor=child;

 	   container[child].left_neighbor=left;

 	   container[right].left_neighbor=last_child;

 	   container[last_child].right_neighbor=right;

 	   makeroot(child);

 	 }

 	 minimum=right;

 	 balance();

        } // the case where there are more roots

      } 

    }

    void erase (const Item& it) {

      int i=iimap.get(it);

      if ( i >= 0 && container[i].in ) { 

        if ( container[i].parent!=-1 ) {

 	 int p=container[i].parent;

 	 cut(i,p);	    

 	 cascade(p);

 	 minimum=i;     //As if its prio would be -infinity

        }

        pop();

      }

    }

    void decrease (Item it, PrioType const value) {

      int i=iimap.get(it);

      if ( i >= 0 && container[i].in ) { 

        if ( comp(value, container[i].prio) ) {

 	 container[i].prio=value;

 	 if ( container[i].parent!=-1 ) {

 	   int p=container[i].parent;

 	   if ( !comp(container[p].prio, value) ) { 

 	     cut(i,p);	    

 	     cascade(p);

 	     if ( comp(value, container[minimum].prio) ) minimum=i; 

 	   }

 	 } 

        }

      } else push(it, value);

    }

     void increase (Item it, PrioType const value) {

       int i=iimap.get(it);

       if ( i >= 0 && container[i].in ) { 

 	if ( comp(container[i].prio, value) ) { 

 	  erase(it);

 	  push(it, value);

 	}

       } else push(it, value);

     }

   private:

     void balance() {      

     int maxdeg=int( floor( 2.08*log(double(container.size()))))+1;

     std::vector<int> A(maxdeg,-1); 

     /*

      *Recall that now minimum does not point to the minimum prio element.

      *We set minimum to this during balance().

      */

     int anchor=container[minimum].left_neighbor; 

     int next=minimum; 

     bool end=false; 

        do {

 	int active=next;

 	int d=container[active].degree;

 	if ( anchor==active ) end=true;

 	next = container[active].right_neighbor;

 	if ( !comp(container[minimum].prio, container[active].prio) )

 	  minimum=active;

 	while (A[d]!=-1) {

 	  if( comp(container[active].prio, container[A[d]].prio) ) {

 	    fuse(active,A[d]); 

 	  } else { 

 	    fuse(A[d],active);

 	    active=A[d];

 	  } 

 	  A[d]=-1;

 	  ++d;

 	}

 	A[d]=active;

        } while ( !end );

   }

     /*

      *All the siblings of a are made roots.

      */

     void makeroot (int c)  

     {

       int s=c;

       do {  

 	container[s].parent=-1;

 	s=container[s].right_neighbor;

       } while ( s != c );

     }

     void cut (int a, int b) 

     {    

       /*

        *Replacing a from the children of b.

        */

       --container[b].degree;

       if ( container[b].degree !=0 ) {

       int child=container[b].child;

       if ( child==a ) 

 	container[b].child=container[child].right_neighbor;

       unlace(a);

       }

       /*Lacing i to the roots.*/

       int right=container[minimum].right_neighbor;

       container[minimum].right_neighbor=a;

       container[a].left_neighbor=minimum;

       container[a].right_neighbor=right;

       container[right].left_neighbor=a;

       container[a].parent=-1;

       container[a].marked=false;

     }

     void cascade (int a) 

     {

       if ( container[a].parent!=-1 ) {

 	int p=container[a].parent;

 	if ( container[a].marked==false ) container[a].marked=true;

 	else {

 	  cut(a,p);

 	  cascade(p);

 	}

       }

     }

     void fuse (int a, int b) 

     {

       unlace(b);

       /*Lacing b under a.*/

       container[b].parent=a;

       if (container[a].degree==0) {

 	container[b].left_neighbor=b;

 	container[b].right_neighbor=b;

 	container[a].child=b;	

       } else {

 	int child=container[a].child;

 	int last_child=container[child].left_neighbor;

 	container[child].left_neighbor=b;

 	container[b].right_neighbor=child;

 	container[last_child].right_neighbor=b;

 	container[b].left_neighbor=last_child;

       }

       ++container[a].degree;

       container[b].marked=false;

     }

     /*

      *It is invoked only if a has siblings.

      */

     void unlace (int a) {      

       int leftn=container[a].left_neighbor;

       int rightn=container[a].right_neighbor;

       container[leftn].right_neighbor=rightn;

       container[rightn].left_neighbor=leftn;

     }

     class store {

       friend class FibHeap;

       Item name;

       int parent;

       int left_neighbor;

       int right_neighbor;

       int child;

       int degree;  

       bool marked;

       bool in;

       PrioType prio;

       store() : parent(-1), child(-1), degree(), marked(false), in(true) {} 

     };

   };

 } //namespace hugo

 #endif