#ifndef BIN_HEAP_HH

 #define BIN_HEAP_HH

 #include <vector>

 #include <utility>

 #include <functional>

 namespace marci {

   template <typename Key, typename Val, typename KeyIntMap,

 	    typename Compare = std::less<Val> >

   class BinHeap {

   public:

     typedef Key	             KeyType;

     // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...

     typedef Val              ValueType;

     typedef std::pair<KeyType,ValueType>     PairType;

     typedef KeyIntMap        KeyIntMapType;

     typedef Compare          ValueCompare;

     /**

      * Each Key element have a state associated to it. It may be "in heap",

      * "pre heap" or "post heap". The later two are indifferent from the

      * heap's point of view, but may be useful to the user.

      *

      * The KeyIntMap _should_ be initialized in such way, that it maps

      * PRE_HEAP (-1) to any element to be put in the heap...

      */

     enum state {

       IN_HEAP = 0,

       PRE_HEAP = -1,

       POST_HEAP = -2

     };

   private:

     std::vector<PairType> data;

     Compare comp;

     // FIXME: jo ez igy???

     KeyIntMap &kim;

   public:

     BinHeap(KeyIntMap &_kim) : kim(_kim) {}

     BinHeap(KeyIntMap &_kim, const Compare &_comp) : comp(_comp), kim(_kim) {}

     int size() const { return data.size(); }

     bool empty() const { return size() == 0; }

   private:

     static int parent(int i) { return (i-1)/2; }

     static int second_child(int i) { return 2*i+2; }

     bool less(const PairType &p1, const PairType &p2) {

       return comp(p1.second, p2.second);

     }

     int bubble_up(int hole, PairType p);

     int bubble_down(int hole, PairType p, int length);

     void move(const PairType &p, int i) {

       data[i] = p;

       kim.put(p.first, i);

     }

   public:

     void push(const PairType &p) {

       int n = data.size();

       data.resize(n+1);

       bubble_up(n, p);

     }

     void push(const Key &k, const Val &v) { push(PairType(k,v)); }

     Key top() const {

       // FIXME: test size>0 ?

       return data[0].first;

     }

     Val topValue() const {

       // FIXME: test size>0 ?

       return data[0].second;

     }

     void pop() {

       int n = data.size()-1;

       if ( n>0 ) {

 	bubble_down(0, data[n], n);

       }

       if ( n>=0 ) {

 	data.pop_back();

       }

     }

     const Val get(const Key &k) const {

       int idx = kim.get(k);

       return data[idx].second;

     }

     void put(const Key &k, const Val &v) {

       int idx = kim.get(k);

       if( idx < 0 ) {

 	push(k,v);

       }

       else if( comp(v, data[idx].second) ) {

 	bubble_up(idx, PairType(k,v));

       }

       else {

 	bubble_down(idx, PairType(k,v), data.size());

       }

     }

     void decrease(const Key &k, const Val &v) {

       int idx = kim.get(k);

       bubble_up(idx, PairType(k,v));

     }

     void increase(const Key &k, const Val &v) {

       int idx = kim.get(k);

       bubble_down(idx, PairType(k,v), data.size());

     }

   }; // class BinHeap

   template <typename K, typename V, typename M, typename C>

   int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {

     int par = parent(hole);

     while( hole>0 && less(p,data[par]) ) {

       move(data[par],hole);

       hole = par;

       par = parent(hole);

     }

     move(p, hole);

     return hole;

   }

   template <typename K, typename V, typename M, typename C>

   int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {

     int child = second_child(hole);

     while(child < length) {

       if( less(data[child-1], data[child]) ) {

 	--child;

       }

       if( !less(data[child], p) )

 	goto ok;

       move(data[child], hole);

       hole = child;

       child = second_child(hole);

     }

     child--;

     if( child<length && less(data[child], p) ) {

       move(data[child], hole);

       hole=child;

     }

   ok:

     move(p, hole);

     return hole;

   }

 } // namespace marci

 #endif // BIN_HEAP_HH