/******************************************************************************************[Heap.h]
MiniSat -- Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson

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The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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**************************************************************************************************/

#ifndef Heap_h
#define Heap_h

#include "Vec.h"
#include <iostream>
using namespace std;

//=================================================================================================
// A heap implementation with support for decrease/increase key.


template<class Comp>
class Heap {
  Comp     lt;
  vec<int> heap;     // heap of ints
  vec<int> indices;  // int -> index in heap

  // Index "traversal" functions
  static inline int left  (int i) { return i*2+1; }
  static inline int right (int i) { return (i+1)*2; }
  static inline int parent(int i) { return (i-1) >> 1; }


  inline void percolateUp(int i)
  {
    int x = heap[i];
    while (i != 0 && lt(x, heap[parent(i)])){
      heap[i]          = heap[parent(i)];
      indices[heap[i]] = i;
      i                = parent(i);
    }
    heap   [i] = x;
    indices[x] = i;
  }


  inline void percolateDown(int i)
  {
    int x = heap[i];
    while (left(i) < heap.size()){
      int child = right(i) < heap.size() && lt(heap[right(i)], heap[left(i)]) ? right(i) : left(i);
      if (!lt(heap[child], x)) break;
      heap[i]          = heap[child];
      indices[heap[i]] = i;
      i                = child;
    }
    heap   [i] = x;
    indices[x] = i;
  }


  bool heapProperty (int i) const {
    return i >= heap.size()
      || ((i == 0 || !lt(heap[i], heap[parent(i)])) && heapProperty(left(i)) && heapProperty(right(i))); }


public:
  Heap(const Comp& c) : lt(c) { }

  int  size      ()          const { return heap.size(); }
  bool empty     ()          const { return heap.size() == 0; }
  bool inHeap    (int n)     const { return n < indices.size() && indices[n] >= 0; }
  int  operator[](int index) const { return heap[index]; }

  void decrease  (int n) { percolateUp(indices[n]); }

  // RENAME WHEN THE DEPRECATED INCREASE IS REMOVED.
  void increase_ (int n) {  percolateDown(indices[n]); }


  void insert(int n)
  {
    indices.growTo(n+1, -1);

    indices[n] = heap.size();
    heap.push(n);
    percolateUp(indices[n]); 
  }


  int  removeMin()
  {
    int x            = heap[0];
    heap[0]          = heap.last();
    indices[heap[0]] = 0;
    indices[x]       = -1;
    heap.pop();
    if (heap.size() > 1) percolateDown(0);
    return x; 
  }


  void clear(bool dealloc = false) 
  { 
    for (int i = 0; i < heap.size(); i++)
      indices[heap[i]] = -1;
#ifdef NDEBUG
    for (int i = 0; i < indices.size(); i++)
#endif
      heap.clear(dealloc); 
  }


  // Fool proof variant of insert/decrease/increase
  void update (int n)
  {
    if (!inHeap(n))
      insert(n);
    else {
      percolateUp(indices[n]);
      percolateDown(indices[n]);
    }
  }


  // Delete elements from the heap using a given filter function (-object).
  // *** this could probaly be replaced with a more general "buildHeap(vec<int>&)" method ***
  template <class F>
  void filter(const F& filt) {
    int i,j;
    for (i = j = 0; i < heap.size(); i++)
      if (filt(heap[i])){
	heap[j]          = heap[i];
	indices[heap[i]] = j++;
      }else
	indices[heap[i]] = -1;

    heap.shrink(i - j);
    for (int i = heap.size() / 2 - 1; i >= 0; i--)
      percolateDown(i);

  }


  // DEBUG: consistency checking
  bool heapProperty() const {
    return heapProperty(1); }


  void print() const {
    cout << "_____________________" << endl;
    int i = 2;
    for (int j = 0; j < heap.size(); j++) {
      printf("%3d ", heap[j]);
      lt.print(heap[j]);
      cout << (!(i & (i-1)) ? "\n" : " ");
      i++;
    }
    cout << endl << "_____________________" << endl;
  }      

  // COMPAT: should be removed
  void setBounds (int n) { }
  void increase  (int n) { decrease(n); }
  int  getmin    ()      { return removeMin(); }

};


//=================================================================================================
#endif
