1 /*****************************************************************************/
2 /*!
3 *\file minisat_heap.h
4 *\brief MiniSat internal heap implementation
5 *
6 * Author: Alexander Fuchs
7 *
8 * Created: Fri Sep 08 11:04:00 2006
9 *
10 * <hr>
11 *
12 * License to use, copy, modify, sell and/or distribute this software
13 * and its documentation for any purpose is hereby granted without
14 * royalty, subject to the terms and conditions defined in the \ref
15 * LICENSE file provided with this distribution.
16 *
17 * <hr>
18 */
19 /*****************************************************************************/
20
21 /******************************************************************************************[Heap.h]
22 MiniSat -- Copyright (c) 2003-2005, Niklas Een, Niklas Sorensson
23
24 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
25 associated documentation files (the "Software"), to deal in the Software without restriction,
26 including without limitation the rights to use, copy, modify, merge, publish, distribute,
27 sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
28 furnished to do so, subject to the following conditions:
29
30 The above copyright notice and this permission notice shall be included in all copies or
31 substantial portions of the Software.
32
33 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
34 NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
35 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
36 DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
37 OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
38 **************************************************************************************************/
39
40 #ifndef _cvc3__minisat__heap_h_
41 #define _cvc3__minisat__heap_h_
42
43 //=================================================================================================
44
45 #include "debug.h"
46 #include <iostream>
47
48 // provides a heap over ints
49
50 namespace MiniSat {
51
52
left(int i)53 static inline int left (int i) { return i+i; }
right(int i)54 static inline int right (int i) { return i+i + 1; }
parent(int i)55 static inline int parent(int i) { return i >> 1; }
56
57 template<class C>
58 class Heap {
59 public:
60 C comp;
61 vec<int> heap; // heap of ints
62 vec<int> indices; // int -> index in heap
63
percolateUp(int i)64 inline void percolateUp(int i)
65 {
66 int x = heap[i];
67 while (parent(i) != 0 && comp(x,heap[parent(i)])){
68 heap[i] = heap[parent(i)];
69 indices[heap[i]] = i;
70 i = parent(i);
71 }
72 heap [i] = x;
73 indices[x] = i;
74 }
75
percolateDown(int i)76 inline void percolateDown(int i)
77 {
78 int x = heap[i];
79 while (left(i) < heap.size()){
80 int child = right(i) < heap.size() && comp(heap[right(i)],heap[left(i)]) ? right(i) : left(i);
81 if (!comp(heap[child],x)) break;
82 heap[i] = heap[child];
83 indices[heap[i]] = i;
84 i = child;
85 }
86 heap [i] = x;
87 indices[x] = i;
88 }
89
ok(int n)90 bool ok(int n) { return n >= 0 && n < (int)indices.size(); }
91
92 public:
Heap(C c)93 Heap(C c) : comp(c) { heap.push(-1); }
94
setBounds(int size)95 void setBounds (int size) { DebugAssert(size >= 0, "MiniSat::Heap::setBounds"); indices.growTo(size,0); }
inHeap(int n)96 bool inHeap (int n) { DebugAssert(ok(n), "MiniSat::Heap::inHeap"); return indices[n] != 0; }
97
increase(int n)98 void increase (int n){
99 DebugAssert(ok(n), "MiniSat::Heap::increase: ok");
100 DebugAssert(inHeap(n), "MiniSat::Heap::increase: inHeap");
101 percolateUp(indices[n]);
102 }
103
empty()104 bool empty () { return heap.size() == 1; }
105
insert(int n)106 void insert(int n) {
107 DebugAssert(n > 0, "MiniSat::Heap::insert: inserting invalid var id");
108 if (!inHeap(n)) {
109 DebugAssert(ok(n), "MiniSat::Heap::insert: ok");
110 indices[n] = heap.size();
111 heap.push(n);
112 percolateUp(indices[n]);
113 }
114 }
115
getMin()116 int getMin() {
117 int r = heap[1];
118 DebugAssert(r > 0, "MiniSatHeap:getmin: invalid var id");
119 heap[1] = heap.last();
120 indices[heap[1]] = 1;
121 indices[r] = 0;
122 heap.pop();
123 if (heap.size() > 1)
124 percolateDown(1);
125 return r; }
126
heapProperty()127 bool heapProperty() {
128 return heapProperty(1); }
129
heapProperty(int i)130 bool heapProperty(int i) {
131 return (size_t)i >= heap.size()
132 || ((parent(i) == 0 || !comp(heap[i],heap[parent(i)])) && heapProperty(left(i)) && heapProperty(right(i))); }
133 };
134
135 }
136
137 //=================================================================================================
138 #endif
139