1 | /************************************************************************
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2 |
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3 | Heap data structure
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4 |
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5 | Copyright (C) 1998 Michael Garland. See "COPYING.txt" for details.
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6 |
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7 | $Id: MxHeap.cxx,v 1.1 2002/09/24 16:53:54 wimmer Exp $
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8 |
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9 | ************************************************************************/
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10 |
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11 | //#include "stdmix.h"
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12 | #include "MxHeap.h"
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13 |
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14 |
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15 | ////////////////////////////////////////////////////////////////////////
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16 | //
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17 | // Internal functions for manipulating the heap
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18 |
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19 | inline void MxHeap::place(MxHeapable *x, unsigned int i)
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20 | {
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21 | ref(i) = x;
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22 | x->set_heap_pos(i);
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23 | }
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24 |
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25 | void MxHeap::swap(unsigned int i, unsigned int j)
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26 | {
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27 | MxHeapable *tmp = ref(i);
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28 |
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29 | place(ref(j), i);
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30 | place(tmp, j);
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31 | }
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32 |
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33 | void MxHeap::upheap(unsigned int i)
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34 | {
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35 | MxHeapable *moving = ref(i);
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36 | uint index = i;
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37 | uint p = parent(i);
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38 |
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39 | while( index>0 && moving->heap_key() > ref(p)->heap_key() )
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40 | {
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41 | place(ref(p), index);
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42 | index = p;
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43 | p = parent(p);
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44 | }
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45 |
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46 | if( index != i )
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47 | place(moving, index);
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48 | }
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49 |
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50 | void MxHeap::downheap(unsigned int i)
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51 | {
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52 | MxHeapable *moving = ref(i);
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53 | uint index = i;
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54 | uint l = left(i);
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55 | uint r = right(i);
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56 | uint largest;
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57 |
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58 | while( l<length() )
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59 | {
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60 | if( r<length() && ref(l)->heap_key() < ref(r)->heap_key() )
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61 | largest = r;
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62 | else
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63 | largest = l;
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64 |
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65 | if( moving->heap_key() < ref(largest)->heap_key() )
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66 | {
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67 | place(ref(largest), index);
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68 | index = largest;
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69 | l = left(index);
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70 | r = right(index);
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71 | }
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72 | else
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73 | break;
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74 | }
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75 |
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76 | if( index != i )
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77 | place(moving, index);
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78 | }
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79 |
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80 | ////////////////////////////////////////////////////////////////////////
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81 | //
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82 | // Exported interface to the heap
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83 | //
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84 |
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85 | void MxHeap::insert(MxHeapable *t, float v)
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86 | {
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87 | t->heap_key(v);
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88 |
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89 | unsigned int i = add(t);
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90 | t->set_heap_pos(i);
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91 |
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92 | upheap(i);
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93 | }
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94 |
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95 | void MxHeap::update(MxHeapable *t, float v)
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96 | {
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97 | SanityCheck( t->is_in_heap() );
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98 | t->heap_key(v);
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99 |
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100 | unsigned int i = t->get_heap_pos();
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101 |
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102 | if( i>0 && v>ref(parent(i))->heap_key() )
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103 | upheap(i);
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104 | else
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105 | downheap(i);
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106 | }
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107 |
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108 | MxHeapable *MxHeap::extract()
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109 | {
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110 | if( length() < 1 ) return NULL;
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111 |
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112 | swap(0, length()-1);
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113 | MxHeapable *dead=drop();
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114 |
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115 | downheap(0);
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116 | dead->not_in_heap();
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117 | return dead;
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118 | }
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119 |
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120 | MxHeapable *MxHeap::remove(MxHeapable *t)
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121 | {
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122 | if( !t->is_in_heap() ) return NULL;
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123 |
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124 | int i = t->get_heap_pos();
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125 | swap(i, length()-1);
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126 | drop();
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127 | t->not_in_heap();
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128 |
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129 | if( ref(i)->heap_key() < t->heap_key() )
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130 | downheap(i);
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131 | else
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132 | upheap(i);
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133 |
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134 | return t;
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135 | }
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