minisat_heap.h

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/*****************************************************************************/
/*!
 *\file minisat_heap.h
 *\brief MiniSat internal heap implementation
 *
 * Author: Alexander Fuchs
 *
 * Created: Fri Sep 08 11:04:00 2006
 *
 * <hr>
 *
 * License to use, copy, modify, sell and/or distribute this software
 * and its documentation for any purpose is hereby granted without
 * royalty, subject to the terms and conditions defined in the \ref
 * LICENSE file provided with this distribution.
 * 
 * <hr>
 */
/*****************************************************************************/

/******************************************************************************************[Heap.h]
MiniSat -- Copyright (c) 2003-2005, Niklas Een, Niklas Sorensson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

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
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/

#ifndef _cvc3__minisat__heap_h_
#define _cvc3__minisat__heap_h_

//=================================================================================================

#include "debug.h"
#include <iostream>

// provides a heap over ints

namespace MiniSat {


static inline int left  (int i) { return i+i; }
static inline int right (int i) { return i+i + 1; }
static inline int parent(int i) { return i >> 1; }

template<class C>
class Heap {
public:
  C        comp;
  vec<int> heap;     // heap of ints
  vec<int> indices;  // int -> index in heap
  
  inline void percolateUp(int i)
  {
    int x = heap[i];
    while (parent(i) != 0 && comp(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() && comp(heap[right(i)],heap[left(i)]) ? right(i) : left(i);
      if (!comp(heap[child],x)) break;
      heap[i]          = heap[child];
      indices[heap[i]] = i;
      i                = child;
    }
    heap   [i] = x;
    indices[x] = i;
    }
  
  bool ok(int n) { return n >= 0 && n < (int)indices.size(); }

public:
  Heap(C c) : comp(c) { heap.push(-1); }
  
  void setBounds (int size) { DebugAssert(size >= 0, "MiniSat::Heap::setBounds"); indices.growTo(size,0); }
  bool inHeap    (int n)    { DebugAssert(ok(n), "MiniSat::Heap::inHeap"); return indices[n] != 0; }

  void increase  (int n){
    DebugAssert(ok(n), "MiniSat::Heap::increase: ok");
    DebugAssert(inHeap(n), "MiniSat::Heap::increase: inHeap");
    percolateUp(indices[n]);
  }

  bool empty     ()         { return heap.size() == 1; }
  
  void insert(int n) {
    DebugAssert(n > 0, "MiniSat::Heap::insert: inserting invalid var id");
    if (!inHeap(n)) {
      DebugAssert(ok(n), "MiniSat::Heap::insert: ok");
      indices[n] = heap.size();
      heap.push(n);
      percolateUp(indices[n]);
    }
  }
  
  int getMin() {
    int r            = heap[1];
    DebugAssert(r > 0, "MiniSatHeap:getmin: invalid var id");
    heap[1]          = heap.last();
    indices[heap[1]] = 1;
    indices[r]       = 0;
    heap.pop();
    if (heap.size() > 1)
      percolateDown(1);
    return r; }
  
  bool heapProperty() {
    return heapProperty(1); }
  
  bool heapProperty(int i) {
    return (size_t)i >= heap.size()
      || ((parent(i) == 0 || !comp(heap[i],heap[parent(i)])) && heapProperty(left(i)) && heapProperty(right(i))); }
};

}

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